Suspending a Connection in a Wireless Communication System

ABSTRACT

An evolved Node B (eNB) includes a memory and at least one hardware processor communicatively coupled with the memory and configured to: determine to suspend an established radio resource control (RRC) connection with a user equipment (UE), where suspension causes the established RRC connection to be a suspended RRC connection that disables user plane data communications between the UE and the eNB; in response to a determination to suspend the established RRC connection, store RRC connection data related to the established RRC connection; and transmit, to the UE, an RRC connection suspend command instructing the UE to store the RRC connection data and suspend the established RRC connection.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system and inparticular the handling of connections between nodes in a wirelesscommunication system.

BACKGROUND

Wireless communications systems are known that enable wireless datatransfer between one or more user equipment (UE) and one or more BaseStations (BS) arranged to provide nodes of a cellular RAN. An increasein the prevalence of UEs operating on wireless cellular communicationssystems squires that such networks carry and support a wide variety ofdata traffic types and services. UEs can be viewed as generic computingplatforms with wireless connectivity, capable of running a wide-rangingvariety of applications and services that are either pre-installed bythe device manufacturer or are installed/downloaded by the useraccording to the user's specific usage requirements. The applicationsthemselves may originate from a correspondingly wide-ranging group ofsoftware houses, manufacturers and 3^(rd) party developers. Such UEplatforms may include mobile devices such as mobile telephones,‘smartphones’ personal digital assistants, handheld or laptop computers,tablet computers and similar mobile devices having wirelesscommunications connectivity, or similarly the UE referred to hereincould include fixed devices that are relatively immovable in normal use,such liked devices having wireless connectivity to enable them tocommunicate using the wireless communications system. The UE platformsmay also include other device types comprising embedded communicationsconnectivity, such as household appliances, utility meters and securityand surveillance equipment, or consumer electronics devices such asstill or video cameras, audio/visual entertainment equipment and gamingplatforms.

Wireless communication networks often distinguish between user-planetraffic (which may be considered as carrying application-level userdata) and control-plane traffic (which may be considered as signallingused to enable or support transfer of the user plane data via thewireless communication network, including for example mobility controland Radio Resource Control (RRC) functionality). Examples of user planetraffic and services carried by wireless communication networks includevoice, video, internet/web browsing sessions, upload/download filetransfer, instant messaging, e-mail, navigation services, RSS feeds andstreaming media. Examples of control plane traffic include core-networkmobility and attachment control (so-called Non-Access Stratum (MAS)signaling), radio access network control (such as Radio Resource Control(RRC)), and session control signalling.

Outside of for “above”) the radio and core network communication layers,applications, may utilise or combine a multitude of internet-based forother proprietary) protocols to achieve a desired result whenprovisioning for a specific service. For example, a navigationapplication may utilise TCP for file transfer of mapping data from aserver to a device but may also employ protocols to support periodic oraperiodic keep-alive signalling towards the navigation server tomaintain the application-level connection in the presence ofintermediary network nodes such as stateful firewalls. Similarly, ane-mail application may employ particular synchronisation protocols toalign the mailbox contents on the UE with those in an e-mail server, butmay also employ periodic or aperiodic server polling mechanisms to checkfor new e-mail. The present disclosure concerns operating wirelesscommunication systems to provide UEs With connectivity to support suchapplications.

For a more complete understanding of this disclosure, reference is nowmade to the following detailed description that sets out certainembodiments, taken in connection with the drawings, which can be brieflydescribed as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system including an LTE RadioAccess Network coupled to an Evolved Packet Core Network, furthercoupled to an external packet data network such as the public internet.

FIG. 2 shows a block diagram of selected components of an example UE foruse in a wireless communication system in accordance with the presentdisclosure.

FIG. 3 shows an illustration of a control manager in a RAM of the UEshown in FIG. 2 for facilitating communications with a wirelesscommunication system in accordance with the present disclosure.

FIG. 4 illustrates the RRC connection states, DRX sub-states and thetransitions therebetween in LTE.

FIG. 5 is a message sequence chart illustrating a normal RRC connectionprocedure in a wireless communication system in which no RRC connectionsuspension functionality is provided.

FIG. 8 is a flow diagram illustrating a simplification of the RRCconnection process in a wireless communication system in which no RRCconnection suspension functionality is provided.

FIG. 7 is a flow diagram illustrating a simplification of the RRCconnection reactivation process in a wireless communication system inwhich RRC connection suspension functionality is provided in accordancewith the present disclosure.

FIG. 8 is a message sequence chart illustrating an exemplary RRCconnection suspension process in a wireless communication system inaccordance with the present disclosure.

FIG. 9 is an illustration of an exemplary mobility scenario for handlingby the mobility handling process signalling variants during RRCconnection suspension in accordance with the present disclosure.

FIG. 10 is a message sequence chart illustrating an example ofsignalling variant 1 in mobility processing alternative B in a wirelesscommunication system in which a UE has a suspended RRC connection.

FIG. 11 is a message sequence chart illustrating an example ofsignalling variant 2 in mobility processing alternative B in a Wirelesscommunication system in which a UE has a suspended RRC connection.

FIG. 12 is a message sequence chart illustrating an example ofsignalling variant 3 in mobility processing alternative B in a wirelesscommunication system in which a UE has s suspended RRC connection.

FIG. 13 is an illustration of another exemplary similar to FIG. 9 inwhich the UE moves back into, and again out of, a cell of the RAN inwhich the suspended RRC connection is valid.

FIGS. 14, 15 and 16 are message sequence charts illustrating methods forhandling downlink (DL) data in the network in different scenarios whenthe RRC Connection between a UE and a RAN are suspended.

FIGS. 17, 18 and 19 show message sequence charts illustrating RRCreactivation methods for handling the resumption of user plane datatransfer for a UE having a suspended RRC Connection with a RAN.

FIG. 20 show a message sequence chart illustrating the method ofhandling an RRC connection suspension in Example Scenario 1.

FIG. 21 snows a message sequence chart illustrating the method ofhandling an RRC connection suspension in Example Scenario 2.

FIG. 22 shows a message sequence chart illustrating the method ofhandling an RRC connection suspension in Example Scenario 3.

DETAILED DESCRIPTION

Many UE applications require or benefit from so-called always-onconnectivity, such that a seamless and continuous connection experienceis delivered to the user when using the UE and the applications runningthereon. Whist the appearance of seamlessness is presented to the userat the service level, this may in fact be accomplished without permanentor continuous connectivity at all protocol levels beneath theapplication layer. Instead, it may be the case that connections areestablished and released on a regular or as-needed basis in order todeliver the user data when required but to allow for certain powerefficiency or system efficiency savings in the UE during the interveningperiods of time. However, a frequent establishment and release of theseconnections may also entail significant use of system resources orresult in additional signalling loads within the network, and theassociated system resource and control overheads may become large. Forsome application traffic, this may counteract the power or systemefficiency benefits of employing such an “as-needed” connectionestablishment strategy. Systems and methods which are able to reducethese system resource and control overheads are therefore desirable suchthat overall system and power efficiencies are improved when attemptingto deliver a seamless user or service experience at the applicationlevel via the communications network.

The prevalence of a plethora of application types, services, end meansof service delivery in wireless communications systems results in acorresponding plethora of data traffic distributions and statistics thatare presented to the wireless communication networks for delivery.Wireless communication networks are therefore less able to predicttraffic profiles and distributions, and must be designed to adapt theconnections and the assigned transmission resources to the dynamicallyvarying (potentially “bursty”) traffic loads.

In order to do so, wireless radio access networks can include dynamicscheduling such that a quantity of assigned shared radio resources maybe varied in rapid response to data demand (e.g. data buffer status).Such dynamic scheduling typically operates on a time scale of one to afew milliseconds. At a time-scale above this (operating in the region of100 ms to a few seconds), wireless communication networks often alsoemploy a state machine-oriented process to adapt a radio connectionstate or sub-slate to the degree of observed traffic activity. Radioconnection states or sub-states may differ in numerous ways, including:the degree of connectivity offered, the quantity of system resourcesthat are reserved or used for the connection, and the amount of UEbattery power consumed.

The connectivity level can be characterised as a combination of variousconnectivity attributes such as:

-   -   Location granularity: The accuracy to which the wireless        communication network, tracks the current location of the UE        (e.g. to the cell level for more active UEs, or to only a group        of cells for less active UEs)

Mobility control: The decision to change the cell to which the UE isassociated may be taken by the network (network controlled mobility) orby the UE (UE controlled mobility), in the case of network controlledmobility a UE may be instructed to perform measurements and reportmeasurement results to the network in order to assist the network inmaking the decision to perform a handover. Once a handover decision ismade the network will typically prepare any necessary resources in thetarget cell before instructing the UE to change cell by sending ahandover command, in the case of UE controlled mobility, the UE willperform measurements on neighbouring cells and use these measurements inmaking a decision to perform a cell reselection. The network can controlthe decision process by sending various cell rejection parameters (e.g.threshold, offsets, etc) in broadcast system information. Networkcontrolled mobility (handover) requires more over the air signaling,network internal signalling, and network processing resource than UEcontrolled mobility.

-   -   Assigned resources: The presence, absence, type or amount of        radio transmission resources available to the UE for performing        communication, as a function of expected activity level    -   Tx/Rx Readiness: The power consumed by UEs is often a function        of their “readiness” to transmit or receive. For example, a UE        must permanently activate its receiver in order to receive        downlink communication from a basestation if the data may arrive        at any given instant, resulting in high power consumption and        battery drain. To save power, discontinuous reception (DRX) is        often employed, allowing the UE to “sleep” and turn off its        receiver at certain times. The basestation (BS) must take the        UE's DRX pattern into account when determining the times at        which it will be able to successfully deliver data to the UE.        The activity cycle of a DRX pattern often varies as a function        of the assigned radio connection state or sub-state.    -   Interfaces or bearers established: End-to-end communications        (for example from a UE to a core network gateway or egress node        towards external networks such as the internet) may require that        user-specific connections (or bearers) are established between        all participating network nodes or entities. The establishment        of some of these interfaces may be associated with the radio        connection state or sub-state as a function of the current        activity level.

Disclosed herein are methods, apparatuses and software for use in aWireless communications system to suspend and handle the reactivation ofa Radio Resource Control (RRC) connection for carrying user-plane andcontrol plane data between a UE and a RAN. Also disclosed herein aremethods, apparatuses and software for handling mobility control anddownlink data for a UE for which an RRC connection is suspended.

Long Term Evolution (LTE) is a Third Generation Partnership Project(3GPP) standard for wireless communication network technology. Anillustrative example of a wireless communication system 100 supportingcommunications in accordance with LTE is shown in FIG. 1.

The following detailed description is set out in the context of awireless communication system supporting LTE, but it should heunderstood that the applicability of the present disclosure is in no waylimited to LTE. Indeed the broad concepts of UE-RAN RRC connectionsuspension and handling thereof disclosed herein are equally applicablein other wireless communication systems supporting other technologiesand protocols, whether currently known or not yet envisaged. In thisrespect, the disclosure should in no way be limited to the followingillustrative implementations, drawings and techniques, but may bemodified and used in other wireless communication systems withoutdeparting from the scope of the appended claims, due regard being givento all equivalents.

LTE describes a plurality of requirements for wireless communicationssystems in evolved or advanced cellular broadband technologies. Suchrequirements include providing an Evolved Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access Network(E-UTRAN)—i.e. RAN 102. As shown in FIG. 1, RAN 102 provides ahigh-speed radio access technique to support wireless communicationsbetween UE 101 and one or more BS acting as nodes of the RAN 102 to meetthe increased network demands. Including improving user throughputs andnetwork capacity, reducing latency, and increasing mobility. The LTE RAN102 shown in FIG. 1 comprises one node type acting as the node basestations (BS)—i.e. evolved Node Bs (eNB) 102 a,b . . . n, advanced LTEequipment that supports an E-UTRAN air interface, and which can provideat least some of the functionalities of the BS, wireless access points,and other systems and devices some of which may be more evolved than theequivalent equipment in a traditional wireless telecommunicationssystem. The term eNB or access device may be used herein to refer to anydevice, existing or advanced, that may be used to gain access to anetwork. Such advanced or next generation equipment may be referred toherein as long-term evolution (LTE) equipment.

An eNB may support communications with UEs via one or more cells. Acommunication between an eNB and a UE may comprise communication via asingle cell of the eNB or may comprise simultaneous or non-simultaneouscommunication via more than one cell.

In some implementations, the functionality of an eNB may beself-contained within one physical node or entity, whilst in otherimplementations, said functionality may be distributed between more thanone physical node or entity with interconnections therebetween.

As can be seen in FIG. 1, the LTE wireless communication network 100provides a Uu radio interface between the UE 101 and the eNB 102 a ofthe RAN 102 to facilitate radio communications therebetween.

LTE uses an Evolved Packet Core (EPC) network architecture for the CoreNetwork (CN) 103 to support the RAN 102 (in the LTE case, the E-UTRAN),Thus, as shown in FIG. 1, the eNB RAN nodes 102 a,b . . . n formconnections with one or more nodes in the EPC CN 103 (described below).The EPC network architecture transports protocols such as TransmissionControl Protocol (TCP)/internet Protocol (IP) for supporting IP basedservices, such as voice, video, other media, and messaging, withend-to-end Quality of Service (QoS). The EPC network architecture alsoenables improved connections add hand-over to other fixed-line andwireless access technologies with improved mobility.

The LTE Radio Access Network 102 (E-UTRAN) coupled to an EPC CN 103 maybe further coupled to an external packet data network such as the publicinternet 104.

The EPC CN 103 shown in FIG. 1 comprises three node types—the ServingGateway (SGW) 103 a routes user-plane data within the core network, theMobility ManagementEndpoint (MME) 103 b handles mobility and connectioncontrol between the UE and the core network, and the Packet Gateway(PGW) 103 c ingress/egress node routes data between the core network andexternal networks. During a communications session between the UE 101,eNB 102 a and CN 103 an ‘S1’ network interface between the RAN 102 andCN 103 is formed, including a control plane bearer connection ‘S1-MME’(sometimes referred to as ‘S1c’) ‘S1-MME’ between the eNB 102 a and MME103 b, and a user plane bearer connection ‘S1u’ between the eNB 102 aand SGW 103 a. An ‘S5/S8’ interface between the SGW 103 a and PGW 103 cprovides user plane communications therebetween. MME 103 b may beconnected to SGW 103 a, for example via an ‘S11’ interface.

FIG. 2 shows a block diagram illustrating some example componentscomprised in an example UE 200 that can be used in the LTE-enabledwireless communications system as shown in FIG. 1. The UE 200 may be awireless device and its associated Universal Integrated Circuit Card(UICC) that includes a Subscriber Identity Module (SIM) application, aUniversal Subscriber identity Module (USIM) application, or a RemovableUser identity Module (R-UIM) application or the UE 200 might be thedevice itself without such a card.

UE 200 includes multiple components linked by a communications bus 201.A processor 202 controls the overall operation of the UE 200.Communication functions, including data and voice communications, areperformed through a communication subsystem 204, The communicationsubsystem 204 may take the form of modems, modem banks, Ethernetdevices, universal serial bus (USB) interface devices, serialinterfaces, token ring devices, fiber distributed data interface (FDDI)devices, wireless local area network (WLAN) devices, radio transceiverdevices such as code division multiple access (CDMA) devices, globalsystem for mobile communications (GSM) radio transceiver devices,worldwide interoperability for microwave access (WIMAX) devices, and/orother well-known devices for connecting to networks. The communicationsubsystem 204 may enable the processor 202 to communicate with theinternal or one or more telecommunications networks or other networksfrom which the processor 202 might receive information or to which theprocessor 202 might output information. In the context of FIG. 1, thecommunication subsystem 204 receives messages from and sends messages towireless network 206 which may be the RAN 102 shown in FIG. 1 for voicecommunications or data communications or both. A power source 208, suchas one or more rechargeable batteries or a port to an external powersupply, powers the UE 200.

The processor 202 interacts with other components of the electronicdevice including Random Access Memory (RAM) 210, mass storage 212(including but not limited to magnetic and optical disks, magnetic tape,solid state drives or RAID arrays), Read Only Memory (ROM) 214 anddisplay screen 216, which may be, for example, a Liquid Crystal Display(LCD). An i/o controller 218 sends and receives signals relative to oneor more user control devices, such as a touch sensitive overlay on thedisplay screen 216 to enable user interaction with the UE 200.

The processor 202 executes instructions, code, software or computerprograms it may access from communications subsystem 204, RAM 210, massstorage 212 or ROM 214. The processor 202 may comprise one or more dataprocessing units or CPU chips. The processor 202 may execute theinstructions solely by itself, or in concert with other locally orremotely provided data processing components or other components notshown in FIG. 2. In particular, the processor 202 is capable of carryingout instructions such that the UE 200 is operable to perform wirelesscommunications in an LTE network in accordance with the disclosure setout below.

For example, referring to FIG. 3, the processor 202 may carry outinstructions to instantiate and maintain a communications manager 301 inRAM 210 that in use operates the communications subsystem 204 to performsignalling to interact with RAN 102.

The communications manager 301 may instantiate, for example in the RAM110 of UE 201, an LTE protocol stack to provide, at the Access Stratumlayers of LTE, one or more of a Radio Resource Control (RRC) signallinglayer 302 that is typically responsible for the control of radio relatedfunctions, a Radio Link Control (RLC) signalling layer 303 that istypically responsible for the retransmission of lost data, a MediumAccess Control (MAC) signalling layer 304 that is typically responsiblefor controlling access to the Physical Layer (PHY) 305. Of course,layers of the protocol stack may be implemented elsewhere, for examplethe MAC and PHY signalling may be provided in the UE by firmware orhardware and so not maintained m RAM 110. Indeed, the implementation ofthe protocol stack in the UE shown in FIG. 3 is only one example of manypossibilities within the scope of the present disclosure, and isprovided for explanatory purposes only.

The LTE Physical Layer (PHY) uses advanced technologies, includingOrthogonal Frequency Division Multiple Access (OFDMA), multiple-inputand multiple-output (MIMO) delta transmissions, and smart antennas tomeet the network demands above. The LTE PHY uses OFDMA for downlinktransmissions, for instance from a BS to a UE, which can communicate bytransmitting signals throughout a geographical region known as a cell.Additionally, Within one carrier, the LTE PHY uses Single CarrierFrequency Division Multiple Access, (SC-FDMA) for uplink transmissions,for instance from the UE to the BS. The OFDMA and SC-FDMA technologiesfacilitate in increase in the system capacity and throughput whenperforming communications via an associated spectrum or bandwidth.

As mentioned a hove, the LTE system includes protocols such as a RadioResource Control (RRC) protocol, which is responsible for theassignment, configuration and release of connections and radio resourcesbetween the UE 101 and the eNBs 102 a,b, . . . n of RAN 102 or otheraccess or LTE equipment. The RRC protocol is described in detail in the3GPP TS 36.331 specifications. According to the RRC protocol, the twobasic RRC connection modes for the UE in LTE are defined as “idle mode”and “connected mode.”

During the connected mode or state, the UE 101 may exchange signals withthe network and perform other related operations, including the abilityto perform user-plane communications with the network, while during theidle mode or state, the UE 101 may shut down at least some of itsabilities and operations, and is no-longer able to perform user-planecommunications with the network. Idle and connected mode behaviours aredescribed in detail in the Third Generation Partnership Project (3GPP;specifications TS 36.304 and TS 36.331.

FIG. 4 illustrates the RRC state transitions for LTE. Transitionsbetween idle mode 401 and connected mode 402 in LTE are effected viaexplicit RRC connection establishment 403 (or setup) and release 404procedures and involve associated signalling overheads. During normalidle mode procedures, should a need for user plane communications arise,an RRC connection is established via the currently-camped cell. Thesequence of messages exchanged during a normal RRC connectionestablishment to transition between idle mode and connected mode in LTEis shown in FIG. 5. If the connection is UE-originated, an RRCconnection request message is sent (initiated using the PRACH randomaccess channel) by UE 101. Conversely, if the connection isnetwork-originated, the MME 103 a first requests for all eNBs 102 a,b .. . n within the known tracking area to send a paging message to the UE101 in order to stimulate the UEs sending of an RRC connection requestmessage.

Within the Connected Mode 402, UE 101 may implement DRX procedures,these being controlled within the Medium Access Control (MAC) layer. TheDRX pattern is defined via the use of multiple timers arid processesthat may be triggered by data activity or other events. However, theoverall degree of DRX may be conceptualised to exist in one of threepredominant modes, wherein one of these modes may be in use at any onetime. It is therefore possible to consider these DRX modes as MACsub-states of the RRC connected mode 402, each associated with a DRXlevel:

-   -   Continuous Reception 402 a: No DRX—the receiver of UE 101 is        always on and ready to receive user plane data over the RRC        connectors.    -   Short DRX 402 b: The UE is allowed to turn off its receiver        (sleep, or DRX) for all but M out of N sub-frames (where a        sub-frame is a 1 ms unit of transmission time in the LTE        system), where M is a small value, such a 1 or 2, end N is a        relatively small value, such as 8.    -   Long DRX 402 c; The UE is allowed to turn off its receiver        (sleep, or DRX) for all but M out of N sub-frames, where M is a        small value, such a 1 or 2, and N is a relatively large value,        such as 256.

For correct system operation it is important that both the eNB 102 a andthe UE 101 are synchronised as to which sub-frames are categorised asDRX (the UE 101 may sleep) and which are not (the UE 101 may not sleep).To enable such co-ordination, inactivity timers may be configured (inboth the UE 101 and the eNB 102 a). In order to implicitly control (i.e.without signalling commands or orders) transitions towardsConnected-Mode DRX sub-states with increased DRX. In addition, MACcommands may also be used by the network (sent from eNB 102 a to the UE101) in order to explicitly direct a transition to an increased DRXsub-state.

When in the connected mode 402, any communication of new user plane datatypically results in a transition to the continuous reception sub-state402 a for a period of time determined by the ongoing packet dataactivity and m inactivity timer known as the DRX-InactivityTimer. Eachnew data packet resets the DRX-InactivityTimer to a preconfigured valueand when the timer expires, a transition from continuous reception 402 ato one of the DRX sub-states 402 b, 402 c is made.

In the LTE system, the mechanisms used to control UE mobility betweencells of the network differs between the idle 401 and connected 402modes:

-   -   In idle mode 401, mobility is UE-controlled (i.e. the UE 101        performs cell selection and reselection procedures as per 3GPP        Technical Specification 36.304 and in accordance with related        configuration parameters set by the network). Following        selection or reselection of a new cell by the UE 101, the UE 101        will inform the network of its new location only if the new cell        belongs to a tracing area that is different from the tracking        area of the previous camped cell. A tracking area is a group of        cells—which cells belong to which tracking area is dependent        upon network configuration. Thus, in idle mode 401, mobility        reports are only seldom sent by the UE 101, and the network is        aware of the UE's location with relatively coarse granularity        (tracking area level as opposed to cell level).    -   In connected mode 402, the UE 101 performs measurements of other        cells (on the same or other frequencies) according to the        configuration sent to the UE 101 by the network in measurement        control messages. The measurements are reported by the UE 101 to        the network wherein they are used by the network to make        handover decisions. Subsequent to a handover decision by the        network, the UE 101 is instructed to move to another cell or        frequency. Thus, in connected mode 402, measurement reports may        be sent relatively frequently and the network is aware of the        UE's location with finer granularity (to the cell level).

The RRC and MAC/DRX sub-states for LTE are summarised in Table 1 below.

TABLE 1 LTE Radio Core RRC/ Access Network MAC Bearers Bearers State/Estab- Estab- Radio sub- lished lished Resources Location Mobility state(Uu, S1) (S5/S8) Available Accuracy Control DRX Connected, Yes Yes YesCell Network No Cont. Rx Connected, Yes Yes Yes Cell Network Short ShortDRX (return to sleep continuous) Connected, Yes Yes Yes Cell NetworkLong Long (return to sleep DRX continuous) Idle No Yes No Tracking UELong Area sleep

As will be evident from the description below, the present disclosuresets out a method, usable in, for example, an LTE wireless communicationnetwork, of suspending an RRC connection such that at least user planecommunications between the UE and eNB are disabled (i.e. not able to betransmitted or received by the UE and the eNB), but in which thesuspended RRC connection can be efficiently reactivated such thatcommunications between the UE and eNB are resumed across the same‘established’ RRC connection, without a new RRC connection having to becreated. This provides significant advantages for wirelesscommunications systems for the following reasons.

Some applications running on UEs may generate traffic that requires theprovision of transmission resources only infrequently or for shortperiods of time, Traffic of this nature may be characterised as ‘bursty’or ‘sporadic’ and may involve extended periods of time with little or nodata activity. When handling such traffic within the system, frequentRRC state transitions from idle mode 401 to connected mode 402 for theUE 101 would each involve significant signalling exchanges between theUE 101 and the RAN 102, and/or between the RAN 102 and the CN 103. Thesignalling may for example be needed to:

-   -   1. establish or reconfigure Radio Bearers (e.g. over the Uu        interface between the UE 101 and the RAN 102)    -   2. establish or reconfigure other bearers, bearer segments, or        communication paths (e.g. the S1 bearer(s) between an LTE eNB        102 a,b . . . n and the SGW 103 a. or the S5/8 bearer(s) between        the SGW 103 a and PGW 103 c)    -   3. carry out security procedures to establish secure        communications

If, for reasons of network efficiency, the UE 101 were kept always inRRC connected mode 402 while handling such traffic, such that repeatedstate transitions and the related network messaging overhead describedabove were avoided, this could lead to high power usage and shorterbattery life for the UE 101 due to the relatively high powerrequirements of being always on in RRC connected mode 402. This ispartly because in RRC connected mode 402 mobility is always networkcontrolled at the cell level (which involves measurement reporting fromthe UE). In addition, although DRX cycles (controlled by the MAC layer)may be employed to reduce UE power consumption during times of datainactivity, mobility still remains network controlled and also, theconnected-mode DRX configuration is set by the network and may notprovide the UE With power consumption comparable to that of idle mode401. Furthermore, some radio transmission resources may be assigned,reserved or used by the UE for control signalling purposes when inconnected mode even though there may be no immediate user-plane data fortransmission. The connected mode DRX sub-state may thus exhibitexcessive power consumption for the UE 101 or inefficient use of systemresources for the RAM 102, whilst a transition to idle mode 401 (andsubsequently back to connected mode 402 on resumption of data activity)may incur significant signalling overheads to execute.

As will be evident from the following description, suspending the RRCconnection, as set out in the present disclosure, provides advantagesover these two techniques of controlling wireless communication systemsparticularly during so-called ‘bursty’ or sporadic data transfer to UEs(i.e. repeated state transitions or of holding the UE in a DRX sub-stateof connected mode 402), such that, in the present disclosure, networktraffic and power consumption can be relatively low and battery life canbe relatively high.

In the present disclosure, rather than a UE 101 that is in a connectedmode 402 but which is temporarily inactive (i.e. due to no immediatedata transfer being needed during an inactive time period of bursty orsporadic communications) transitioning to an idle mode 401 or to aconnected mode DRX sub-state 402 a, 402 b. the UE 101 instead isconfigured to perform UE controlled mobility (UE autonomous cellselection/reselection) and DRX procedures as if it were in idle mode(the idle mode configuration is reused thereby obviating the need for anew RRC state definition or configuration). However, whilst behaving asif in idle mode, the RRC connection for the UE may be considered to be“suspended” (as opposed to released). The difference between an RRCsuspension and an RRC release is that all of the RRC configurationinformation is not discarded but is instead stored by both the eNB 102 aand the UE 101. The stored (suspended) RRC configuration may comprise,for example, parameters relating to the current configuration of radiobearers, radio resources, temporary cell identifiers and/or securityparameters or keys. Thus one or more (note: not necessarily all-)components of a radio connection “context” still exists in memory withinthe eNB 102 a and UE 101, but these may be labelled as ‘inactive’,‘dormant’ or ‘suspended’. This may mean that one or more of the storedRRC configuration parameters may not be used for immediate user planecommunications between the UE 101 and the eNB 102 a without executing astep of determining their current validity.

In the proposed solution, should a need for user plane communicationsarise for a UE with a suspended RRC context, the RRC connection may onlybe used (by the network or UE as appropriate) following a precursorycheck as to whether the suspended RRC context is currently valid(corresponding to one or more components of the RRC connection contextbeing stored in memory by the UE 101 and eNB 102 a). If a validsuspended RRC context does exist, the RRC connection may be freed fromsuspension (i.e. ‘reactivated’) and is again ready for immediate usesuch that user plane communications between the UE 101 and eNB 102 a maybe resumed without the need for extensive RRC reconfiguration,establishment or setup procedures. An “RRC-reactivation” message orprocedure is required to resume user plane data transfer (using thepreviously-stored RRC connection configuration) within the cell, if thepre-existing (‘established’), suspended, RRC connection is valid and canbe reactivated, no new RRC connection needs to be created in order tocontinue to handle the user plane communications. This is particularlyuseful when handling bursty-type data traffic, and can significantlyconserve power and keep control plane traffic associated with RRCconnection handling low. During the reactivation procedure it is alsopossible that one or more components of the stored RRC connection areupdated.

If a valid suspended RRC context does not exist, or if it is determinedthat many components of the stored RRC connection would requireupdating, normal RRC connection establishment procedures are followed aswould be the case for a normal idle mode UE (i.e. RRC connection setupfollowing either a random access or paging procedure).

A simplified view of this RRC reactivation process is shown in the flowchart of FIG. 7. This may be contrasted to the normal RRC connectionsetup procedures from idle mode shown in FIG. 6, where no RRC suspensionfunctionality is provided in the wireless communication network. Bycomparing the flow chart of FIG. 7 with FIG. 6 if can be seen that, inaccordance with the present disclosure, subsequent to the suspension ofan RRC connection, when a need for user plane data communication arisesand it is determined that a suspended RRC connection is ‘valid’, thiscan be successfully reactivated by an RRC connection reactivationprocess. Various RRC connection validity criteria may first be checkedin the UE 101 or the eNB 102 a or in both before the RRC connectionreactivation process is triggered. Also due to the fact that a valid S1interface must also exist prior to communication of user plane data,nodes of the CN 103 (such as the MME 103 b) may also be involved inchecking the validity status of the suspended RRC connection whenreactivation is required. Examples of validity criteria that may beemployed as inputs to the decision process are listed below:

-   -   Whether the UE 101 is currently camped on the same cell as the        cell to which it was connected when the RRC context was        suspended. Typically, an RRC configuration applies on a per cell        basis and so this check can be used to ensure that the context        remains valid (i.e. the cell hasn't changed). Note that this        does not exclude the possibility for the UE 101 to have moved        out of the cell in which the RRC context was suspended, and back        in again to the same cell. In these cases the RRC context may        still be reactivated and is considered a valid suspended RRC        context.    -   Whether the UE 101 is currently camped on the same group of        cells as the group of cells to which it was connected when the        RRC context was suspended. An eNB 102 a,b . . . n would        typically support multiple cells, allowing for significant        co-ordination between those cells at the radio resource        management and RRC level without the need for standardised        interfaces. Thus a UE's RRC context information may be visible        to a group of cells (such as in the same eNB 102 a,b . . . n)        and an operator or network vendor may choose to coordinate some        aspects of the RRC configuration between them. This could enable        an RRC connection that was suspended within one cell under an        eNB 102 a to be resumed under another cell of the same eNB        102 a. In scenarios such as this, knowledge of whether a UE 101        is still attached to the same eNB 102 a,b . . . n (or other        defined group of cells) may be useful when checking whether a        suspended RRC connection is still valid at the time it needs to        be reactivated. The group of cells may alternatively comprise a        tracking area.    -   Whether an elapsed period of time since the RRC connection was        suspended is lower than a predetermined timer expiry threshold.        The system may wish to restrict the length of time for which an        RRC connection may be retained in the suspended state. Suspended        connections with an age beyond a preconfigured value are no        longer considered valid.

As described above, in accordance with the present disclosure a UE 101in a temporarily-inactive connected mode (i.e. having a ‘suspended’ RRCconnection) performs UE-controlled mobility (UE autonomous cellselection/reselection) and DRX procedures as if it were in idle mode,and during this time the RRC connection for this UE may be considered tobe “suspended” (as opposed to released). However, the condition of stateof the UE during this time may of course be viewed in different ways,for example:

-   -   1. The UE 101 may be viewed as being in idle mode (as if        performs UE-controlled mobility and idle mode DRX procedures)        but with some or all of the configuration associated with its        most recent RRC connection remaining stored to allow quick and        efficient reactivation of the old RRC connection under certain        circumstances.    -   2. The UE 101 may be viewed as remaining in the RRC connected        mode but being configured to perform UE-controlled mobility and        DRX procedures similar to idle mode. All or most of the RRC        configuration information remains stored in the UE 101 while        some parts of the RRC configuration may be released.    -   3. The UE 101 may be viewed as remaining in the RRC connected        mode but being placed in a new state or sub state or mode in        which it performs UE-controlled mobility and DRX procedures        similar to idle mode. All or most of the RRC configuration        information remains stored in the UE 101 while some parts of the        RRC configuration may be released.

Indeed, it is not intended that the present disclosure is limited to theUE being considered in the connected mode but with the RRC connection‘suspended’. Rather the present disclosure sets out a methodology ofhandling RRC connections between a UE and a RAN, and the UE-relatedconnections between the RAN and the CN such that transfer of user planedata between the UE and RAN is disabled and the data representing theRRC connection is stored such that user plane data transfer can later beresumed using the same ‘established’ RRC connection without that RRCconnection being ‘released’ (i.e. abandoned) and without a new RRCconnection needing to be created. This methodology can be utilised notjust in wireless communication systems supporting LTE, but also in otherwireless communications protocols.

The methods associated with implementing and supporting the RRCConnection suspension and reactivation procedures of the presentdisclosure will now be described in more detail, including somealternatives and variants that are possible. The procedures associatedwith RRC Connection suspension and reactivation can be divided into fouraspects which are described in the following sections:

-   -   RRC Connection Process    -   Processes Handling mobility (i.e. procedures as the UE moves)        during RRC Connection Suspension    -   Processes Handling receipt of downlink (DL) data during RRC        connection suspension    -   Processes Handling a suspended RRC Connection to resume Uu data        transfer

The methods and other modes of operation described herein of the UE 101eNB 102 a,b . . . n, SGW 103 a, MME 103 b and other CN nodes within thescope of the present disclosure may be provided at least in part by oneor more processors within the UE 101, eNB 102 a,b . . . n, SGW 103 a,MME 103 b and other CN nodes executing machine readable instructions toconfigure them to function accordingly to carry out said methods. Theinstructions may be provided as computer software products. Eachcomputer software product may be provided in, on or supported by acomputer readable medium which could be provided as all possiblepermanent arid non-permanent forms of computer readable medium eithertransitory in nature, such as in a data transmission signal for examplesent over the internet, or non-transitory m nature such as in a RAM orother, non-volatile storage. On the other hand the computer readablemedium may be a non-transitory computer readable medium comprising allcomputer-readable media, with the sole exception being a transitory,propagating signal.

RRC Connection Suspension Process

In the UE 101, when the RRC Connection suspension occurs the UE 101 maybe configured to perform idle mode mobility and paging receptionprocedures while keeping stored for possible re-use some or all of itsRRC context information. In order to maximise the benefits of the RRCConnection suspension procedures, the stored RRC context informationshould include the following:

-   -   The lists of Established Data Radio Bearers (DRBs) and        Signalling Radio Bearers (SRBs) including, for each radio        bearer, the PDCP configuration and current state (e.g. counter        values, etc) and the RLC configuration and status (e.g. counter        values, etc).    -   Security configuration and state (e.g. cipher and integrity        algorithm, counter values, etc)    -   Measurement reporting configuration.    -   Last used cell identity and cell specific user identity (C-RNTI)

In addition, the stored RRC context may also include other informationsuch as (but not limited to) configuration information or parametersrelating to any allocation of radio resources, MAC configuration,physical channel configuration or physical layer configuration data.

Compared to the list above, such information may be more likely tochange from one cell to another and hence there may be less benefit inkeeping this information stored.

In the network, when the RRC Connection Suspension occurs, the eNB 102 aceases to perform connected mode mobility procedures for the UE 101while keeping stored for possible re-use some or ail of the UE's RRCcontext information. The RRC context information stored in the networkshould correspond to that stored in the UE 101. In addition, there aretwo main alternatives to the network side suspension procedure dependingon whether the eNB informs the CN about the suspension at the time itoccurs:

-   -   RRC Connection Suspension Alternative A—CN not informed of        suspension    -    if the CN 103 is not informed of the suspension (by either the        UE 101 or the eNB 102 a), the S1 user plane between the S-GW 103        a and the eNB 102 a will remain active and any inbound        network-originated data will be forwarded by the S-GW 103 a over        the S1 to the corresponding eNB 102 a where it would need to be        buffered pending delivery to the UE 101. It is then the        responsibility of the eNB 102 a to contact and deliver the data        to the suspended UE 101 if the suspended UE context is found to        be invalid at this time (e.g. because the UE has moved to        another cell), the eNB 102 a would need to initiate additional        procedures (involving the CN 103) to locate the UE 101 and to        route the data to the correct eNB 102 b . . . n and onward to        the UE 101 (procedures for contacting the UE 101 in this        situation are discussed below). Alternatively, rather than        routing data on towards the correct eNB 102 b . . . n once the        UE 101 is located, the data may be discarded and higher layer        protocols (for example, TCP/IP) may instead be relied upon to        ensure eventual delivery.    -   RRC Connection Suspension Alternative B—CN informed of        suspension    -    If the CN 103 is informed of the suspension (e.g. by either the        UE 101 or the eNB 102 a), it may take action to also suspend the        S1 user plane between the S-GW 103 a and the eNB 102 a. The S1        user plane suspension may only affect the way that the S-GW 103        a treats DL user data arriving in the S-GW 103 a. Hence, in this        case it may be considered as just a DL S1 user plane suspension        such that any inbound network-originated data is buffered at the        S-GW 103 a pending delivery to the UE 101. It is then the        responsibility of the CN 103 (i.e. MME 103 b and/or S-GW 103 a)        to identify the location of the UE and to subsequently contact        and deliver the data to the suspended UE 101.

The CN 103 would typically be notified of a suspension through receiptof a notification message from the eNB 102 a, it is also possible thatthe UE 101 could inform the CN 103 of a connection suspension (e.g.following its receipt of a suspend message from the eNB 102 a), althoughthis may be less preferable due to the fact that this would involveadditional signalling over the air interface.

A CN node (e.g. MME 103 b and/or S-GW 103 a) may maintain a validityindicator for each UE (effectively this may relate either to whether anactive S1 user plane exists for the UE, or to the current, validitystatus of a suspended S1 user plane for the UE). As mentioned in section5, this indicator may be set based upon one or more separatesub-criteria such as location-based criteria or timer-based criteria.The location-based validity criteria may involve for example recording acell or eNB 102 a,b . . . n from which the RRC suspend notification wasinitially received and setting the location validity indicator to TRUEif the currently-known location of the UE 101 matches the validitycriteria, and setting the location validity indicator to FALSEotherwise. The timer-based validity criteria may involve setting atimer-based validity indicator to TRUE if an elapsed time since the RRCconnection suspension (or S1 connection suspension) is lower than athreshold value and to FALSE, otherwise. By means of example, theoverall validity criteria may comprise setting an overall validityindicator to TRUE if both the location validity indicator and thetimer-based validity indicator are TRUE, and setting the overallvalidity indicator to FALSE otherwise.

An example message sequence chart of events related to an RRC Connectionsuspension is shown in FIG. 8. Steps E-G of the process described below(but not all shown in FIG. 8) are only carried out if the CN 103 isinformed of the suspension (otherwise these steps are omitted). Thesteps of the RRC connection suspension process shown in FIG. 8 can bedescribed as follows:

-   -   A. A UE 101 is in connected mode.    -   B. Data activity for the UE 101 ceases temporarily (e.g. due to        ‘bursty’ communications by an application running on UE 101).    -   C. The UE's RRC Connection is suspended. This may be achieved        via implicit mechanisms such as the expiry of an inactivity        timer in both the eNB 102 a and the UE 101, or via explicit        mechanisms such as the sending of a message or command from the        eNB 102 a to the UE 101 to instruct the suspension of the RRC        Connection. In the explicit case, the suspend message may be        sent by the eNB 102 a in response to a network inactivity timer        expiry, or as the result of other events such as the receipt of        an indication from the UE that it expects no more data to send.        In the implicit case, the eNB 102 a and UE 101 enter the suspend        state at approximately the same time but no suspend message need        be sent.    -   D. The UE 101 and eNB 102 a suspend the RRC connection. The Uu        connection is effectively ‘deactivated’ such that no user plane        data is transferred between the eNB 102 a and UE 101 but RRC        configuration information is stored by both the UE 101 and the        eNB 102 a. The UE 101, however, continues to monitor for paging        or notification of downlink data (see below).    -   E. The eNB 102 a may optionally send an S1 user-plane suspend        message to the MME 103 b and/or SGW 103 a (possibly via the MME)        to inform the CN 103 of the RRC suspension. The message may        include fields to identify the one or more UEs and possibly        bearer identifiers that have been suspended.    -   F. The MME 103 b may deactivate (but store in memory) the        existing S1-MMS (S1c) bearer context associated with the UE 101.        ‘Deactivating’ is understood here to mean that data ceases to be        transferred over the bearer.    -   G. The SGW 103 a deactivates (but stores in memory) existing        S1-u user plane bearer contexts associated with the UE. Again,        ‘deactivating’ is understood here to mean that data ceases to be        transferred over the bearer.

Specific actions taken by the CM 103 in response to receipt of an S1suspend may therefore include:

-   -   Deactivating (but storing,, pending reactivation) one or more S1        user plane and/or S1-MME bearer contexts in the SGW 103 a and        MME 103 b respectively, or in eNB 102 a    -   Buffering of any network-originated user data at the SGW 103 a        pending resumption of the S1 user plane    -   Monitoring for inbound tracking area or other location/cell        updates at the MME 103 b from the UE who's RRC connection has        been suspended (in order to assist with determining validity        status in the event of a need for reactivation)

In order for the RRC Connection suspend process above to be used, boththe UE 101 and the network of the wireless communication system need tobe configured to support this functionality. An RRC Connectionsuspension support indicator may be included a UE capabilities messagethat is transferred from the UE 101 to the network. Alternatively,support for RRC connection suspension in the UE may be implicitlyinferred by the eNB as the result of the UE indicating support foranother (but associated) feature or UE capability within the UEcapability message. If the UE capability message indicates that the UEsupports the RRC Connection suspend functionality then the eNB 102 a canchoose to configure the UE 101 with appropriate parameters to triggerimplicit suspension (e.g. via configuration of a suspension timer value)or the eNB 102 a can choose to send the explicit RRC Connection suspendmessage, eNB 102 a may also choose to configure the UE 101 such that RRCsuspension procedures or components of the RRC suspension behaviours areeither allowed or disallowed.

Processes Handing Mobility During RRC Connection Suspension

On suspension of a UE's RRC connection, the UE 101 performs cellselection and reselection in a similar manner to that of a normal idlemode UE 101 (i.e. the UE 101 follows the general mobility procedures ofTS 36.304). However, if location-based validity criteria are used, thenthe UE 101 can be aware when the UE 101 selects/reselects a cell inwhich its suspended RRC Connection is not valid (e.g. a cell where theeNB 102 b . . . n controlling that cell does not have the stored contextinformation for that UE).

An example is shown in FIG. 9 where the UE 101 is initially on Cell Aunder eNB1 102 a (point 1). The RRC Connection is suspended. The UE 101reselects from Cell A, under eNB1 102 a, to Cell B, also under eNB1 102a (point 2). From the location based validity criteria, the UE 101 knowsthat its suspended RRC Connection is still valid and hence need take noaction. The UE 101 then reselects from Cell B to Cell C which is under adifferent eNB, i.e. eNB2 102 b (point 3). From the location basedvalidity criteria, the UE 101 knows that its suspended RRC Connection isno longer valid at point 3. At this point, there are two mainalternative mobility handling process for how the UE 101 acts during RRCconnection suspension. The UE 101 may be configured to only perform oneof the following methods, or selectively perform either method.

-   -   Mobility Alternative A—Do not inform the network that the UE is        outside of the area where its Suspended RRC Connection is valid    -    Although at point 3 the UE 101 is aware that it is outside the        area where it knows its suspended RRC Connection is valid, the        UE 101 does not initiate any signalling towards the network.        Instead, the UE 101 continues to perform UE-based mobility and        paging reception procedures and continues to keep its stored RRC        Context Information. In mobility alternative A, as long as the        UE 101 remains Within a registered tracking area (TA) of cells        then cell reselections do not trigger any signalling towards the        network (i.e. the network is not made aware of the        reselections). However, the UE 101 would still need to perform a        Tracking Area Update (TAU) if it moved outside of its registered        TA(s), just as it would have to do if it were in idle mode. A TA        would typically cover many cells and many eNBs 102 a, b, . . .        n. The RRC Context information remains stored so that it can        potentially be used if, at the time that data activity is        resumed, the UE 101 has returned to a cell where the suspended        RRC Connection is valid.    -   Mobility Alternative B—Inform the network that the UE is outside        the area where its Suspended RRC Connection is valid    -    When, at point 3, the UE 101 is aware that it is outside the        area where it knows its suspended RRC Connection is valid, the        UE 101 in this alternative initiates some signalling to inform        the network. Under mobility alternative B, the signalling        procedures adopted by the UE 101 can, for example, be one of the        following three variants:        -   Signalling Variant 1—Discard suspended RRC connection,            perform NAS procedure and return to idle.        -   On the new cell under eNB2 102 b, in this variant the UE 101            discards its suspended RRC connection and performs            signalling by initiating a Non Access Stratum (NAS)            procedure (e.g. an LTE ‘TAU’ procedure). This may be an            unmodified TAU procedure or may be a TAU procedure modified            to include a cause value indicating the reason for sending            the TAU (i.e. the UE has identified that the suspended RRC            connection is no longer valid). This TAU procedure causes            the MME 103 b to release the S1 connection to eNB1 102 a and            the eNB1 102 a to release the suspended RRC Connection. At            completion of the TAU procedure the UE 101 is placed into            idle mode and hence has no RRC Connection with any eNB 102            a,b . . . n.        -   Signalling Variant 2—Discard suspended RRC connection,            perform NAS procedure and remain RRC connected.        -    On the new cell under eNB2 102 b, in this variant the UE            101 discards its suspended RRC connection and performs            signalling by initiating a NAS procedure (e.g. TAU or            Service Request). This may be an unmodified TAU or Service            Request or may be a modified TAU or service request modified            to include a cause value indicating the reason for            initiating the procedure (i.e. the UE has identified that            the suspended RRC connection is no longer valid). This            TAU/Service Request causes the MME 103 b to release the S1            connection to eNB1 102 a and causes eNB1 102 a to release            the suspended RRC Connection. The MME 103 b initiates new            access stratum security and establishment of data radio            bearers (DRBs) and establishment of an S1 user plane            connection to eNB2 102 b. At completion of the TAU/Service            Request, the UE 101 remains in RRC Connected with eNB2            102 b. The eNB2 102 b may choose to suspend the RRC            Connection as described above, such that the new RRC            connection between the UE 101 and eNB2 102 b is suspended.            If so, the state of the UE 101 at point 3 in FIG. 9 would            then be the same as it was at point 1 but with an RRC            Connection with eNB2 102 b instead of eNB1 102 a.        -   Signalling Variant 3—Maintain suspended RRC connection,            perform signalling to inform CN of mobility        -    On the new cell under eNB2 102 b, in this variant the UE            101 maintains its suspended RRC context and performs            signalling by initiating a procedure in order to inform the            CN 103 that the UE 101 has a currently-invalid suspended RRC            Connection. This procedure could be a NAS procedure—for            example, k could be an unmodified TAU or a TAU containing a            new indication that the UE 101 has an invalid suspended RRC            Connection, or it could be a new NAS message such as “NAS            Mobility Update” message. Alternatively, this could be an            access stratum (AS) procedure that in turn triggers the eNB2            102 b to inform the CN 103 that the UE 101 has a            suspended-but-currently-invalid RRC connection—for example            it could be an new “RRC Mobility Update” message sent from            UE to eNB2 102 b, or it could be an existing RRC message            containing a new “Mobility Update Indicator”, then followed            by an “S1 Mobility Update” message from eNB2 102 b to MME            103 b. Whatever form the signalling takes the purpose of the            procedure is that it will cause the S-GW 103 a to suspend            the S1 user plane. At completion of the procedure the UE 101            remains with its suspended RRC connection but is camped on            eNB1 102 a. Note that in order to perform the TAU procedure            the UE may or may not have had to create an RRC Connection            with eNB2 102 b and an S1 connection with the MME 103 b. If            such connections do need to be created, this may be            considered as a temporary RRC Connection that gets discarded            at the completion of the TAU or other update message. If the            MME 103 b were to establish access stratum security and            establish DRBs then this temporary RRC Connection would            become the ‘permanent’ RRC Connection and the suspended RRC            Connection would be discarded.

Message sequence charts for the above three signalling variants (1, 2,3) are shown in FIG. 10, FIG. 11 and FIG. 12 respectively. The initialsteps of these charts are the same with the differences between thethree variants occurring within the areas identified by rectangleshaving rounded ends.

Signalling variant 1, shown in FIG. 10, can be described as follows.

-   -   1. The UE 101 initially has a suspended RRC Connection with eNB1        102 a.    -   2. UE 101 performs cell reselection to a cell under the control        of eNB2 102 b    -   3. Following cell reselection the UE 101 determines that it is        now in a cell where its suspended RRC Connection may not be        valid.    -   4. The UE 101 releases its suspended RRC Connection for eNB1        102 a. UE 101 enters idle mode.    -   5. The UE 101 initiates a TAU. To perform the TAU the UE 101        first establishes an RRC Connection with eNB2 102 b and then        sends the Tracking Area Update Request. The MME 103 b responds        with a Tracking Area Update Accept.    -   6. Following the completion of the TAU procedure, the UE 101        returns back to idle mode.    -   7. The MME 103 b also sends an S1 release command to eNB1 102 a        to inform it that it can releases its suspended RRC Connection        for the UE 101 and/or release any active or suspended S1        connections for the UE 101.        Signalling variant 2, shown in FIG. 11, can be described as        follows.    -   1. The UE 101 initially has a suspended RRC Connection with eNB1        102 a.    -   2. UE 101 performs cell reselection to a cell under the control        of eNB2 102 b.    -   3. Following the cell reselection, the UE 101 determines that it        is now in a cell where its suspended RRC Connection may not be        valid;    -   4. The UE 101 releases its suspended RRC Connection for eNB1        102 a. UE 101 enters idle mode.    -   5. The UE 101 initiates a TAU of Service Request procedure. To        perform the TAU or Service Request procedure the UE 101 first        establishes an RRC Connection with eNB2 102 b and then sends the        Tracking Area Update Request or Service Request. The MME 103 b        responds by triggering the establishment of access stratum        security and the establishment of the DRBs and the S1 user plane        with eNB2 102 b. The figure shows the Service Request procedure        although the TAU procedure would be quite similar. Note the        figure does not label the individual messages that make up the        overall procedure.    -   6. Following the completion of the TAU or Service Request        procedure, the UE remains in RRC Connected with eNB2 102 b.    -   7. The MME 103 b also sends an S1 release command to eNB1 102 a        to inform it that it can release its suspended RRC Connection        for the UE 101 and/or release any active or suspended S1        connections for the UE 101.        Signalling variant 3, shown in FIG. 12, can be described as        follows.    -   1. The UE 101 initially has a suspended RRC Connection with eNB1        102 a.    -   2. UE 101 performs cell reselection to a cell under the control        of eNB2 102 b.    -   3. Following the cell reselection, the UE 101 determines that it        is now in a cell where its suspended RRC Connection may not be        valid.    -   4. The UE 101 maintains, its suspended RRC Connection for eNB1        102 a.    -   5. The UE 101 initiates signalling to inform the CN 103 that the        UE 101 has a suspended RRC Connection but has moved outside the        area where its suspended RRC Connection is known to be valid.        The example in FIG. 12 shows the UE 101 establishing a        ‘temporary’ RRC Connection and in the RRC Connection Setup        Complete message the UE 101 includes a ‘Mobility Update        Indicator’ although other alternatives are possible including        the use of a TAU procedure (in which case signalling variant 3        is similar to signalling variant 1 with the exception that the        suspended RRC connection is maintained following the UEs        reselection to a cell under control of eNB2 102 b and is not        released—i.e. the procedure is as per signalling variant 1 but        without execution of steps 4, 6 and 7).    -   6. From reception of the Mobility Update Indicator the eNB2 1020        is aware of the purpose of this RRC Connection Establishment and        sends an S1 Mobility Update message to the MME 103 b. In        response to this the MME 103 b sends an S1 user plane suspend        message to the S-GW 103 a.    -   7. On receipt of the S1 user plane suspend message the S-GW 103        a knows that DL data for this UE 101 should be buffered, and the        UE 101 located before the data can be delivered (i.e. the S-GW        103 a should not simply forward the DL data over the S1 to eNB1        102 a as there is a possibility that the UE 101 will not be        located under eNB1 102 a).    -   8. eNB2 102 b instructs the UE 101 to release the ‘temporary’        RRC Connection. The UE 101 still maintains its suspended RRC        connection for eNB1 102 a but is camped on a cell under eNB2 102        b.

A consequence of both signalling variants 1 and 2 is that the UE 101releases the suspended RRC Connection and initiates a signallingprocedure as soon as it moves out of the area where the suspended RRCConnection is known to be valid. Whenever data activity resumes, it willbe necessary for a new RRC Connection (and Security and DRBs) to beestablished before data transfer can begin. Therefore signallingvariants 1 and 2 may not be very effective at reducing signalling loadif the UE is moving.

A benefit of signalling variant 3 compared to variants 1 and 2 isfurther explained by reference to FIG. 13, which shows a mobilityscenario similar to that shown in FIG. 9, in which a UE 101 with asuspended RRC connection moves out of its cell to a point 3 in anothercell in which the RRC connection is invalid, but the FIG. 13 scenarioadditionally shows the UE 101 moving to points 4 and 5. As explainedabove, with signalling variant 3 at point 3 the UE 101 has a suspendedRRC Connection associated with eNB1 102 a and has signalled to thenetwork that it has moved to out of the area where it knows itssuspended RRC Connection is valid. The S-GW 103 a has suspended the S1user-plane to eNB1 102 a.

In the FIG. 13 mobility scenario, after moving to point 4 the UE 101reselects back to cell B which is under the control of eNB1 102 a. Nosignalling needs to be initiated towards the network. If data activitywere to resume at this point, then the suspended RRC Connection witheNB1 102 a could be reactivated. Similarly, the S1 connection betweenSGW 103 a and eNB1 102 a could also be reactivated if it had beenpreviously suspended.

In the FIG. 13 mobility scenario, after moving to point 5 whilst the RRCconnection with eNB1 102 a remains suspended, the UE 101 reselects backto cell C which is under the control of eNB2 102 b. Although the UE 101is again moving outside the area where it knows its suspended RRCConnection is valid, there is no need to initiate any signalling. Thisis because the S1 user plane connection between SGW 103 a and eNB1 102 ahas already been suspended at the S-GW 103 a (this having occurred onthe transition from point 2 to point 3). If data activity were to resumeat this point, then the suspended RRC Connection with eNB1 102 a wouldbe released and a new RRC Connection would need to be established witheNB2 102 b.

It can be seen that with signalling variant 3, signalling towards thenetwork is only required the first time that the UE 101 moves out of thearea where it knows that its suspended RRC Connection is valid, andwhilst the RRC connection remains suspended, subsequent moves in and outof the area can be performed without any signalling. Hence, thisapproach is effective at reducing signalling that may otherwise beassociated with a UE 101 that is located close to a boundary of 2 cellswhere ‘ping-pong’ reselections between the cells could occur.

As an extension to sign ailing variant 3, the UE could be configured toadditionally perform signalling towards a RAN or CN node whenever itmoves back in to a cell or group of cells for which the suspended RRCconnection is again valid (e.g. a cell under the control of eNB1 102 a).This could enable a suspended S1 connection between SGW 103 a and eNB1102 a to be reactivated. The benefits in doing so may be marginalhowever and hence the normal signalling variant 3 may be the preferredoption.

The above procedures may be supplemented with timer based expiry of asuspended RRC connection. For example, a timer may be started at thetime of suspension, or at the time of leaving a suspension cell (orgroup of cells). When the timer expires, the UE 101 (and eNB 102 a,b . .. n and CN 103 nodes) discard any UE 101 context information and the UE101 returns to normal idle operation. If common timers are used withinboth the UE 101 and the eNB 102 a,b . . . n or CN 103 nodes) this maytake place without any signalling between the UE 101 and the any of theRAN or CN nodes. If the timers are implemented only at the eNB 102 a,b .. . n or CN 103 node side, signalling may be required for the RAN or CNnodes to inform the UE that the suspended RRC connection is beingreleased and to instruct a return to idle.

Some possibilities within the signalling variants rely on the use ofexisting procedures (NAS Service Request and TAU) and hence the UE 101can assume that these are supported by the network. However, otherpossibilities within the signalling variants rely ors new signallingfunctionality. In such cases, it may be necessary for the UE 101 to knowthat the eNB2 102 b supports the new signalling before it initiates thatsignalling towards the eNB2 102 b. To address this eNB2 102 b maybroadcast a support indicator in system information. This could be ageneral indicator to indicate support for all the RRC Connectionsuspension functionality or it could just indicate support for the newsignalling functionality (such as the Mobility Update signalling optiondescribed in FIG. 12 for signaling variant 3). If the UE 101 sees thatthe eNB2 102 b does not support the functionality then the UE 101 canfall back to behaving in line with signalling variants that do notrequire new signalling functionality (e.g. the UE could release itssuspended RRC connection and then initiate a TAU or Service Requestprocedure).

In the present disclosure, “releasing an RRC connection” may mean simplyignoring the stored RRC context data, or indicating or marking that dataas being released or invalid, or scrubbing that data, or deleting thedata from memory. Other methods that achieve the same functional effectof releasing an RRC connection are also intended to be within the scopeof the present disclosure.

Handling Receipt of Downlink (DL) Data During RRC Connection Suspension

On suspension of a UE's RRC connection, the UE 101 performs cellselection and reselection in a similar manner to that, of a normal idlemode UE 101 (i.e. the UE 101 follows the general mobility procedures of3GPP TS 36.304). In addition, the UE 101 may monitor the paging channelin exactly the same way as it does in idle mode; i.e. the UE 101 willpower on its receiver at the appropriate paging occasions to attempt toreceive a paging message and then check that paging message for the UE'sidentity (e.g. S-TMSI). On reception of a paging message containing theUE's identity, the UE 101 will attempt to resume its suspended RRCConnection as described below.

When DL data arrives in the network for a UE 101 that has a suspendedRRC Connection, it is necessary that the network can contact or page theUE 101 irrespective of which cell the UE 101 may now be located in.Depending on whether RRC Connection Suspension alternative A or B(described above) is used, and whether Mobility alternative A or B (alsodescribed above) is used, then different scenarios for paging the UE 101when DL data arrives at the S-GW 103 a are possible. Three scenarios forhandling DL data in the network will thus now be described withreference to FIGS. 14 to 16.

FIG. 14 shows a message sequence chart representing a method of handlingDL data in the network when the UE 101 has a suspended RRC Connectionwith eNB1 102 a. The UE 101 is currently located on a cell under eNB1102 a and the S1 user plane between SGW 103 a and eNB1 102 a is notsuspended (1). When DL data arrives at the S-GW 103 a (2), the S-GW 103a forwards the user plane data directly to eNB1 102 a (3). This isnormal S-GW 103 a behaviour for a UE 101 in RRC Connected state. eNB1102 a buffers the DL data (4) and then sends a paging message ornotification of data arrival message to the UE 101 (5). When the UE 101responds to the paging/notification, (e.g. via the sending of an RRCre-activation request) the suspended RRC Connection may be reactivatedand then the eNB1 102 a will be able to deliver the DL data.

FIG. 15 shows a message sequence chart representing a method of handlingDL data in the network when the LTE 101 has a suspended RRC Connectionwith eNB1 102 a. The UE is currently located on a cell under a differenteNB (i.e. eNB2 102 b) and the S1 user plane between SGW 103 a and sNB1102 a is not suspended (1). When DL data arrives at the S-GW 103 a (2),the S-GW 103 a forwards the user plane data directly to eNB1 102 a (3).This is normal S-GW 103 a behaviour for a UE 101 in RRC Connected. TheS-GW 103 a is not aware that the UE 101 has moved or may have moved awayfrom eNB1 102 a and hence the S-GW 103 a is not able to take anyalternative action. eNB1 102 a buffers the DL data (4) and then sends apaging message or notification of data arrival message to the UE 101(5). As the UE 101 is no longer located in a cell under eNB1 then noresponse (in the form of an attempt by the UE to reactivate thesuspended RRC Connection) is received (6). eNB1 102 a send a “pagingescalation” message to the MME 103 b (7) in order to request the MME 103b to page the UE 101 over a wider group of cells (8) (for example theMME 103 b could page the UE 101 in all the cells of the tracking area(s)(TA(s)) in which the UE 101 is registered).

FIG. 16 shows a message sequence chart representing a method of handlingDL data in the network when the UE 101 has a suspended RRC Connectionwith eNB1 102 a and the S1 user plane connection between SGW 103 a andeNB1 102 a is suspended (1). Note that the S1 user plane suspension mayhave occurred as a result of RRC Connection suspension alternative B oras a result of Mobility alternative B with signalling variant 3. The UE101 may be located in a cell under eNB1 102 a (i.e. the eNB where theRRC Connection was suspended) or it may be located under a cell of adifferent eNB 102 b, . . . n. When DL data arrives at the S-GW 103 a(2), the S-GW 103 a buffers this user plane date (3). The S-GW 103 athen initiates a paging procedure towards the MME 103 b to request theMME 103 b to page the UE 101 (4) MME 103 b then pages the UE 101 over awider group of cells, for example it could page the UE 101 in all thecells of the TA(s) in which the UE 101 is registered.

Handling a Suspended RRC Connection to Resume Uu Data Transfer

RRC Connection Reactivation can be triggered by UL data being generatedin the UE101, or by the reception of a paging or DL data notificationmessage indicating that the network has DL data waiting to be delivered.When this occurs the UE 101 first determines whether its suspended RRCConnection is valid for the cell in which it is currently located.Depending on whether the suspended RRC Connection is determined to bevalid, a number of different options are possible.

FIG. 17 shows a message sequence chart representing the RRC reactivationmethod for a UE 101 with a suspended RRC Connection with eNB1 102 a (1).RRC Connection Reactivation is triggered by UL data being generated inthe UE 101, or by the reception of a paging or DL data notificationmessage (2). The UE 101 determines that its suspended RRC Connection isvalid for the cell on which it is located (3). The UE 101 initiates anRRC Connection Reactivation procedure by sending an RRC ConnectionReactivation Request (4). On receipt of this message the eNB1 102 achecks that it has a valid suspended RRC Connection for this UE 101. Ifit has a valid suspended RRC Connection then it sends an RRC ConnectionReactivation message to the UE 101 (5) and the UE 101 responds with anRRC Connection Reactivation Complete message (6). The RRC ConnectionReactivation message may or may not include configuration updates to oneor more of the previously-stored RRC connection parameters for the UE touse following tie reactivation. The UE 101 can now start to send anyuser plane data that it may have buffered (8). If the S1 user plane hadbeen suspended the eNB1 102 a may send an S1 user plane resume messageto the S-GW 103 a (7) (possibly via the MME 103 b as shown as optionalby the dotted lines in FIG. 17) and on receipt of this the S-GW 103 acan resume the S1 user plane and start to forward to the eNB1 102 a anyDL user plane data that may be buffered in the S-CW 103 a (8). As analternative, and if the S1 connection was suspended only in the DLdirection, the reception of UL user plane data from the UE 101 may beused by the S-GW 103 a as an implicit S1 user plane resume message.

FIG. 18 shows a message sequence chart representing another RRCreactivation method for a UE 101 with a suspended RRC Connection witheNB1 102 a (1) but which is no longer valid. RRC Connection Reactivationis triggered by UL data being generated in the UE 101, or by thereception of a paging or DL data notification message (2). In this case,the UE 101 determines that its suspended RRC Connection is not valid forthe cell on which it is located (3) (for example, this may be the caseif the UE 101 is on a cell under eNB2 102 b). The UE 101 releases itssuspended RRC Connection and enters the RRC idle state (4). The UE 101then initiates a normal procedure for establishing an RRC Connectiontowards eNB2 102 b and establishing user plane radio so bearers (i.e.the UE initiates NAS Service Request procedure) (5) and on completion ofthis procedure user plane data transfer is possible (6).

FIG. 19 shows a message sequence chart representing another RRCreactivation method for a UE 101 with a suspended RRC Connection (1),which the eNB1 102 a determines is invalid, RRC Connection Reactivationis triggered by UL data being generated in the UE 101, or by thereception of a paging or DL data notification message (2). The UE 101determines that its suspended RRC Connection is valid for the cell onwhich it is located (3). The UE 101 initiates an RRC ConnectionReactivation procedure by sending an RRC Connection Reactivation Request(4). On receipt of this message the eNB1 102 a checks that it has asuspended RRC Connection for this UE 101 and may also check whether allrequired parameters of the stored RRC connection remain valid. In thiscase the eNB1 102 a determines that it does not have a suspended RRCConnection for the UE 101 or that some of the stored RRC connectionparameters are invalid (5). This may be due, for example, to expiry of avalidity timer in the eNB1 102 a. Alternatively, it may be due to eNB1102 a having assigned some of the resources associated with thesuspended RRC connection to another UE, or due to eNB1 102 a otherwisedetermining that for any valid reason, parts or all of the suspended RRCconnection are no longer valid. In a further alternative. It may due tothe UE 101 accessing an eNB that is different from the one which has theUE's suspended RRC Connection. The eNB1 102 a responds with an RRCConnection Reactivation Reject message (8). The UE 101 releases itssuspended RRC Connection and enters RRC idle mode (7) The UE 101 theninitiates a normal procedure for establishing an RRC Connection andestablishing user plane radio bearers (i.e. the UE 101 initiates a NASService Request procedure) (8) and on completion of this procedure userplane data transfer is possible (9).

It may be necessary for the UE 101 to know that the eNB 102 a,b . . . nsupports the new signalling RRC Connection ReactivationRequest/Setup/Reject signaling before it initiates that signallingtowards the eNB 102 a,b . . . n. To address this, an eNB 102 a,b . . . nmay broadcast a support indicator in system information. This could be ageneral indicator to indicate support for all the RRC Connectionsuspension functionality or it could just indicate support for theRequest/Setup/Reject signalling. If the UE 101 sees that the eNB 102 a,b. . . n does not support the functionality then the UE 101 would releaseits suspended RRC connection and then initiate a Service Requestprocedure.

An alternative to the eNB 102 a,b . . . n broadcasting a supportindicator would be for the eNB 102 a,b . . . n that initially suspendsthe UE's RRC Connection to set the area based validity criteria in a wayto ensure that the UE 101 only attempts to reactivate a suspended RRCConnection on a cell/eNB 102 a,b . . . n that is known to support thefunctionality. In the simplest case the eNB 102 a,b . . . n thatsuspends the UE's RRC Connection would only include in the validitycriteria cells that are located under the same eNB 102 a,b . . . n.

Table 2 below summarises the four possible combinations of RRCConnection Suspension Alternatives A or B with Mobility Alternatives Aor B described above. For each combination, Table 2 describes in whatstatus the RRC Connection and the S1 user plane connection would resideat various points in time. The status of the RRC Connection and S1 userplane may be:

-   -   Idle—no RRC Connection exits, no S1 user piano is established    -   eNB1/2—an RRC Connection exists with eNB1 or eNB2, an S1 user        plane is established between S-GW and eNB1 or eNB2    -   Suspended (eNB1)—a suspended RRC Connection exists with eNB1,        the S1 user plane between S-GW and eNB1 is suspended        The columns of the table T0-T2 relate to different        times/instances and are defined with reference to FIG. 9.    -   T0—UE 101 in location 1 of FIG. 9, before RRC Connection is        suspended    -   T1—UE 101 in location 1 (or location 2, if the UE 101 has        performed cell reselection) of FIG. 9, after RRC Connection is        suspended    -   T2—UE 101 in location 3 of FIG. 9.

TABLE 2 T2 (move to cell under Combination Connection T0 T1 eNB2 whilesuspended) 1/ S1 eNB1 eNB1 eNB1 RRC Sus Alt A, RRC eNB1 SuspendedSuspended (eNB1) Mobility Alt A (eNB1) 2/ S1 eNB1 Suspended Suspended(eNB1) RRC Sus Alt B, (eNB1) Mobility Alt A RRC eNB1 Suspended Suspended(eNB1) (eNB1) 3/ S1 eNB1 eNB1 idle/eNB2/Suspended RRC Sus Alt A, (eNB1)Mobility Alt B RRC eNB1 Suspended idle/eNB2/Suspended (eNB1) (eNB1) 4/S1 eNB1 Suspended idle/eNB2/Suspended RRC Sus Alt B, (eNB1) (eNB1)Mobility Alt B RRC eNB1 Suspended idle/eNB2/Suspended (eNB1) (eNB1)

It should be noted that for combinations 3 and 4 shown in Table 2, threepossible cases are shown for the condition of the RRC and S1 connectionscorresponding to the signalling variants 1/2/3 respectively which may beadopted within Mobility Alternative B.

In addition, it should be noted that combination 4, which corresponds toRRC Connection Suspend alternative B and Mobility alternative B, isshown in the table for completeness. However, with this alternative theS1 user plane is suspended as soon as the RRC Connection is suspended,meaning that any DL data will be buffered at the S-GW 103 a until the UE101 has been paged/notified and has reactivated its RRC Connection. Thusthere may be little benefit to performing any signalling when the UE 101moves to a cell under a different eNB 102 a, b, . . . n.

Given that the various possible processes for handling an RRC connectionsuspension in accordance with the present disclosure have been describedabove, a number of example scenarios will now be described showing howthese various suspended RRC connection handling procedures can operatetogether.

EXAMPLE SCENARIO 1

FIG. 20 shows a message sequence chart representing a possible handlingof the suspension and later attempted reactivation of an RRC connectionbetween UE 101 and a RAN 102 in which (at the time of the reactivationattempt) the UE 101 has moved out of the cell(s) where the suspended RRCconnection is valid in accordance with suspension alternative A (CN notinformed of the RRC suspension) and mobility alternative A (network notinformed of mobility) described above. Due to this processing, the CN103 is not aware that the RRC connection is suspended and hence the S1connection is not suspended. When DL data arrives at the network, thenetwork does not know for certain the cell in which the UE 101 iscurrently located, nor does it know whether any suspended context isvalid. The S1 connection is not suspended end remains active, hence DLdata incident at SGW 103 a is forwarded via S1 to eNB1 102 a. eNB1 102 aattempts to contact the UE 101 via transmission of a paging message andin the absence of a response, a paging escalation approach is used inorder to contact the UE 101. The suspended RRC Connection is not validin the cell in which the UE 101 is found and so it is released and afresh RRC Connection is established for the data to be delivered. Withreference to FIG. 20, the steps of the sequence in this scenario are:

-   -   1. UE 101 is initially in RRC connected with user piano bearers        established such that it is possible for user data to be        transferred between UE 101 and S-GW 103 a and then on to the        P-GW 103 c (not shown in FIG. 20) and beyond.    -   2. Data activity ceases and eNB-1 102 a decides change the UE        101 to UE-controlled mobility and to suspend the RRC connection.    -   3. eNB-1 102 a send a message to the UE 101 to instruct it to        enter UE-controlled mobility and to suspend the RRC connection.        For example this message may be called RRC Connection Suspend as        shown in the Figure, or may be called RRC UE controlled mobility        command, or some other suitable name.    -   4. eNB-1 102 a and UE 101 suspend the RRC connection. The UE 101        performs UE-controlled mobility as if in idle mode.    -   5. When the UE 101 has suspended the RRC connection and enters        UE-controlled mobility, cell reselections may occur. As long as        the UE 101 remains within a registered TA then these        reselections do not trigger any signalling towards the network        (i.e. the network is not made aware of the reselections in        mobility alternative A). Steps 1-5 (excepting the cell        reselections) are indicated in FIG. 20 in the upper rectangle        having rounded ends.    -   6. After a period, when an RRC connection with UE 101 is once        again heeded, in the networking-originated case, user plane data        arrives in the S-GW 103 a. S-GW 103 a immediately forwards the        data on the S1 user plane interface to the eNB1 102 a. On        arrival of the user plane data in the sNB1 102 a the eNB1 102 a        sends a paging message to the UE 101 in order to trigger the RRC        Connection Reactivation. However, in this case eNB-1 102 a does        not receive any response to this paging message, and thus eNB-1        102 a can conclude that the UE 101 is no longer located in a        cell under its control. In order to contact the UE 101 that may        be located in a cell under a different eNB 102 b, . . . n the        eNB-1 102 a must escalate the paging, meaning that it must        trigger the MME 103 b to send paging requests to other eNBs 102        b, . . . n to page the UE 101 within the TA(s) in which the UE        101 is currently registered, in this example scenario in FIG. 20        the escalation causes eNB-2 102 b to send a page and this is        successfully received by the UE 101.    -   7. The UE 101 sends the RRC Connection Reactivation Request to        the eNB-2 102 b. As an alternative Step 7, the UE 101 may be        able to determine prior to sending the RRC Connection        Reactivation Request to the eNB-2 102 b that the reactivation        attempt will not be successful on this cell. For example the UE        101 may be able to determine this from the Cell ID of the cell,        or eNB ID of the cell or some additional indicator that may be        sent in the paging message. If the UE 101 does determine that        the reactivation will not be successful then the UE 101 does not        transmit RRC Connection Reactivation Request but jumps directly        to step 9.    -   8. Due to the fact that in this case the eNB-2 102 b does not        have the UE's suspended RRC Connection, the eNB2 102 b responds        with a RRC Connection Reject.    -   9. The UE 101 releases its (suspended) RRC connection and enters        RRC idle mode. The UE 101 then performs a normal RRC Connection        Establishment procedure in order to setup up a new RRC        connection and continue user plane activity.

EXAMPLE SCENARIO 2

FIG. 21 shows a message sequence chart representing a possible handlingof the suspension and later reactivation of an RRC connection between UE101 and a RAN 102 in which the UE 101 has initially moved out of thecell(s) where the suspended RRC connection is valid (and may havereselected a number of times) but when the data activity is to beresumed the UE 101 is once again camped on a cell where the suspendedRRC Connection is valid and hence it can be successfully reactivated inaccordance with suspension alternative B and mobility alternative Adescribed above.

In accordance with suspension alternative B (CN is informed of the RRCsuspension) and mobility alternative A (network is not informed ofmobility), if the UE 101 reselects away from the cell (or cells) onwhich the suspended RRC connection is valid, the UE 101 does not performany signalling to inform the network (unless the reselection results inthe UE crossing a TA boundary such that a ‘normal’ TAU is needed). Thuswhen DL data arrives the network does not know for certain the cell inwhich the UE is currently located, hence nor does it know whether anysuspended context is valid.

The steps of the sequence are:

-   -   1. UE 101 is initially in RRC connected with user plane bearers        established such that it is possible for user data be        transferred between UE 101 and S-GW 103 a and then on to the        R-GW 103 c (not shown in FIG. 21) and beyond.    -   2. Data activity ceases and eNB-1 102 a decides to change the UE        101 to UE-controlled mobility and to suspend the RRC connection

3. eNB-1 102 a sends a message to the UE 101 to instruct it to enterUE-controlled mobility and to suspend the RRC connection. For examplethis message may be called RRC Connection Suspend as shown in FIG. 21,or may be called RRC UE-controlled mobility command, or some othersuitable name.

-   -   4. eNB-1 102 a and UE 101 suspend the RRC connection. The UE 101        performs UE controlled mobility as if in idle mode.    -   5. eNB-1 102 a informs the CN 103 (MME 103 b or S-GW 103 a or        both) about the RRC suspension. The message to inform the CN 103        may be called S1 user plane suspend. On reception of this by the        CN 103, the S1 user plane bearers remain established but are        suspended (user plane transmission ceases) and the S-GW 103 a,        on reception of downlink user plane data, will not immediately        forward that data over the S1 user plane towards the eNB-1 102 a        and will instead buffer the data pending its delivery. The S1        user plane suspension may only affect the way that the S-GW 103        a treats DL user data arriving in the S-GW 103 a. Hence, in this        case it may be considered as lust a DL S1 user plane suspension.    -   6. When the UE 101 has suspended the RRC connection and enters        UE-controlled mobility, cell reselections may occur. As long as        the UE 101 remains within a registered TA then these reselection        do not trigger any signalling towards the network (i.e. the        network is not made aware of the reselections). Steps 1-6        (excepting the cell reselections) are shown in FIG. 21 in the        upper rectangle having rounded ends.    -   7. In the network-originating case for data transfer activation        with the UE 101, user plane data arrives in the S-GW 103 a. Due        to the S1 user plane suspension, this user plane data is        buffered at the S-GW 103 a instead of being immediately        forwarded on the S1 user plane interface to the eNB-1 102 a. The        S-GW 103 a then initiates a paging procedure to contact the UE        101 in whichever cell it may be located. This is quite similar        (or identical) to the paging procedure used when the UE 101 is        idle. The paging indication is sent from the S-GW 103 a to the        MME 103 b and to one or more eNBs 102 a,b . . . n located within        the TA(s) in which the UE 101 is registered. The reception of a        paging message in the UE 101 triggers the UE 101 to attempt the        RRC Connection Reactivation. This is shown within the lower        rectangle having rounded ends. In the UE-originating case the        elements in the lower rectangle do not occur and the arrival of        user data in at the UE 101 directly triggers the UE 101 to        attempts the RRC Connection Reactivation.    -   8. The remainder of the steps in FIG. 21 represent the sequence        of events when the UE 101 attempts the RRC Connection        Reactivation on a cell where the associated eNB-1 102 a does        have the UE's suspended RRC Connection (i.e. the eNB does have        the stored UE context information). This cell may be the cell        the UE 101 was on when the RRC connection was suspended or it        may be another cell controlled by the same eNB-1 102 a. The UE        101 sends the RRC Connection Reactivation Request to the eNB-1        102 a.    -   9. Due to the fact that in this case the eNB1 102 a does have        the UE's suspended RRC Connection, the eNB-1 102 a responds with        an RRC Connection Reactivation. This message may contain some        new or updated parameter values if the eNB1 102 a wishes to        change any part of the configuration that was previously        suspended, or it may be a very simple ‘continue’ message (e.g.        without any parameter or configuration updates).    -   10. The UE 101 responds with an RRC Connection Reactivation        Complete, This is an optional step, only needed if the eNB-1 102        a requires extra assurance that the RRC Connection Reactivation        has been successful in the UE-originated case, uplink user data        from the UE may start to be transmitted as soon as the RRC        Connection Reactivation has been received.    -   11. The eNB-1 102 a informs the CN 103 (MME 103 b or SGW 103 a        or both) that the S1 user plane can continue. This may be an        explicit message as shown in FIG. 21. Alternatively, in the        UE-originated case, and in the case that only the DL of the S1        was originally suspended, uplink user data from the UE 101 sent        from eNB-1 102 a to S-GW 103 a may be considered as an implicit        ‘continue’ command by SGW 103 a.    -   12. On reception of the indication to continue the S1 user        plane, the S-GW 103 a will stop buffering the downlink user        plane data and will forward it over the reactivated S1 user        plane to the eNB-1 102 a for transmission to the UE 101.

EXAMPLE SCENARIO 3

FIG. 22 shows a message sequence chart representing a possible handlingof the suspension and later reactivation of an RRC connection between UE101 and a RAN 102. The CN 103 is not informed of the RRC suspension, butthe UE 101 does inform the CN 103 when it moves out of the cell(s) wherethe RRC connection is valid. In accordance with suspension alternative Aand mobility alternative B described above.

In summary this shows the method carried out when the UE 101 has movedout of the cell(s) where the suspended RRC connection is valid, and hasinformed the CN 103 about moving out of the suspension cells via amobility update message, so that the S1 is then suspended. When DL dataarrives at the network the UE 101 is paged, the suspended RRC Connectionis net valid in the cell and so it is released and a fresh RRCConnection is established for the data to be delivered.

In this case the CN 103 does not initially know that the UE's RRCconnection has been suspended. A validity indicator may however still bemaintained in the CN 103 for each connected mode UE 101. This indicatormay be set based upon location update information known to the CN 103(e.g. the MME 103 b). Whilst in the connected mode, the CN 103 expectsthat UE 101 mobility events (for example to another cell or eNB 102 b, .. . n) result in a corresponding handover of the S1-U and S1-MME beamsto that eNB. Tracking area updates are expected only from idle mode UEs.Whilst the validity criteria are met, the CN 103 continues to behave asnormal for a connected mode UE 101.

The use of mobility alternative B means that a UE 101 with a suspendedRRC connection (and of which the CN 103 may or may not yet be aware) mayperform autonomous mobility procedures and may be configured to send atracking area update (or other location update) message to the CN 103(e.g. the MME 103 b) in the event that it leaves or re-enters the cell(or group of cells) for which the suspended RRC connection is valid.

If the CN 103 has not been informed at the time of a suspension, the MME103 b initially believes the UE 101 to be still RRC-connected (i.e. notsuspended) unless it learns otherwise. If the UE 101 is configured tosend the additional/augmented mobility messages of mobility alternativeB (e.g. TAU) when suspended, the MME 103 b may subsequently inter fromreceipt of a TAU that the UE's RRC connection has in fact been suspendedand that the UE 101 is currently camped on a cell (or group of cells)for which the suspended RRC connection is not valid. Thus, the MME 103 bis simultaneously and indirectly informed both that the UE's RRCconnection has been suspended and that it is not currently valid. Itwill therefore be appreciated that the signalling ofadditional/augmented mobility messages by the UE 101 may also serve asmessages informing CN nodes (such as MME 103 b and SGW 103 a) of aprevious RRC suspension.

The CN 103 (e.g. MME 103 b) may choose to subsequently suspend the S1connection in such a case. The MME 103 b may optionally reactivate theS1 in the event that it receives a further TAU or mobility message fromthe UE 101 indicating that it has re-entered a call (or group of cells)for which the suspended RRC connection is once again valid.

Within this example scenario 3 a number of different sub-scenarios arepossible depending on whether the data activity causing a need for anRRC connection is network- or UE-originating, and whether the suspendedRRC connection is still valid at the time a reactivation is required.These different sub-scenarios affect how the wireless communicationsystem handles the processing to resume Uu user plane communications.With reference to FIG. 22, the following describes the processing thatoccurs when the data activity is network-originated and the suspendedRRC connection is invalid at the time of required reactivation.Processing for other sub-scenarios may be derived using logicalcombinations of previously described processing steps and is within thescope of the present disclosure.

-   -   1. During RRC connection suspension (shown in the upper rounded        rectangle) the eNB-1 102 a does not inform the CM 103 of the RRC        suspension and the S1 connection is maintained.    -   2. The UE 101 reselects to a cell assigned to eNB-2 102 b in        which the RRC connection is not valid.    -   3. The UE 101 sends an ‘augmented’ mobility message to MME 103        b, possibly via a temporary RRC connection with eNB-2 102 b, or        via other means not requiring establishment of a temporary RRC        connection with eNB2 102 b (middle rectangle).    -   4. On receipt of the mobility message, MME 103 b sends a message        to S-GW 103 a to suspend the existing S1 connection between SGW        103 a and eNB1 102 a. Thus, the MME 103 b and S-GW 103 a have        been implicitly informed that the RRC connection for UE 101 has        been previously suspended and that the suspended RRC connection        is currently invalid.    -   5. Data addressed to the UE 101 arrives from an external network        104 into the PGW 103 c (not shown in FIG. 22).    -   6. The data is forwarded to the UE's SGW 103 a via the        established S5/8 bearer    -   7. The SGW 103 a and MME 103 b are aware that the RRC connection        for this UE 101 is suspended and data is not able to be        forwarded over the (suspended) S1-U connection. Hence the data        is temporarily buffered by the SGW 103 a.    -   8. The CH 103 (e.g. the MME 103 b) checks its locally-stored        validity status for the suspended RRC connection. For example,        this may involve checking a location validity indicator or a        timer-based validity indicator as previously described    -   9. The CN 103 (e.g. MME 103 b) determines that the suspended RRC        connection is not valid.    -   10. The MME 103 b invokes normal idle-mode RRC connection        establishment procedures:        -   a. The MME 103 b sends a paging request to eNBs 102 a,b . .            . n within the currently-known tracking area location of the            UE 101.        -   b. eNBs 102 a,b, . . . n in receipt of the paging request            send a paging message within cells under their control. The            paging message identifies the UE 101 they are attempting to            contact.        -   c. The UE 101 responds to the page in the cell in which it            is currently camped. The UE 101 responds to the page in the            normal way by initiating a normal RRC connection            establishment procedure.        -   d. The eNB-2 102 b (in conjunction with the MME 103 b)            establishes a new RRC connection with the UE 101 and S1-U            and S1-MME; bearers are set up between eNB2 102 b and the            SGW 103 a and the MME 103 b respectively    -   11. The data is transferred over the newly-established S1-U from        the SGW 103 a to the eNB2 102 b (note that the previously-stored        and suspended S1-U may be released)    -   12. The user data is communicated from the eNB-2 102 b to the UE        via the Uu

Aspects of the present disclosure relating to the operation of a UE tosuspend an RRC connection will now be set out in the following numberedclauses.

1. A method, implemented in a user equipment (UE) for use with a RadioAccess Network (RAN), comprising:

the UE suspending an established RRC connection with the RAN;

the UE monitoring, whilst the RRC connection is suspended, for at leastone of: paging and notifications of downlink data for the UE; and

the UE storing RRC connection data related to the suspended RRCconnection, said RRC connection data being usable by the UE toreactivate the suspended RRC connection.

2. A method as set out in clause 1, wherein RRC connection datacomprises data representing one or more of:

-   -   the configuration of radio bearers in the established RRC        connection;    -   security parameters relating to the established RRC connection;    -   temporary cell identifiers;    -   MAG configuration;    -   Physical Layer configuration.        3. A method as set out in clause 1 or 2, further comprising        marking the stored RRC connection data to indicate the        suspension of the RRC connection.        4. A method as set out in clause 1, 2 or 3, wherein the UE        suspends the established RRC connection in response to an RRC        connection suspension criterion being met.        5. A method as set but in clause 4, the RRC connection        suspension criteria comprising one or more of:    -   the expiry of a timer at the UE;    -   reception of a message at the UE.        6. A method as set out in any preceding clause, wherein the RAN        has an established user plane connection with a Core Network        (CN) for the UE, the method further comprising maintaining the        established user plane connection between the RAN and the CN        while the RRC Connection is suspended.        7. A method as set out in clause 8, wherein when the RAN node        for which the suspended RRC connection is valid receives from        the CN downlink data for the UE, the RAN node buffers the        downlink date and pages the UE a transmits a notification of        downlink data for the UE.        8. A method as set out in clause 7, wherein, in response to the        RAN node receiving no response from the UE to the paging or to        the notification of downlink data, the RAN node sends to the CN        a paging escalation message.        9. A method as set out in any of clauses 1 -5, further        comprising the UE or a RAN node sending a message to inform any        node in the Core Network (CN) that the RRC connection is        suspended.        10. A method, as set out in clause 9, wherein the RAN has an        established user plane connection with the CN for the UE, the        method further comprising suspending the established user plane        connection between the CN and the RAN.        11. A method as set out in clause 10, wherein the message sent        to the CN includes an identification of the UE, the method of        suspending the established user plane connection between the CN        end the RAN comprising the RAN or one or more nodes in the CN or        both:    -   discontinuing transmission and reception of user plane data for        the UE over the established user plane connection between the        RAN and the CN; and    -   storing CN-RAN connection data representing the established user        plane connection, said CN-RAN connection data being usable to        later resume transmission and reception of user plane data to        the UE by reactivating said user plane connection between the        RAN and the CN as the result of an RRC connection reactivation        process.        12. A method as set out in clauses 10 or 11, wherein when        downlink data for the is received at the CN, a node of the CN        buffers the downlink data and the CN initiates the paging of the        UE by one or more cells of the RAN.        13. A method as set out in clauses 10, 11 or 12, further        comprising a node of the CN maintaining a validity indicator for        the UE, said validity indicator being usable in checking the        validity of the said RRC connection as part of the RRC        connection reactivation process.        14. A method as set out in clause 13, wherein the value of the        validity indicator is dependent on one or more of: the location        of the UE; a timer.        15. A method as set out in any preceding clause, further        comprising:

the UE performing autonomous mobility control by cell selection orreselection processes during the time that the RRC connection issuspended and the UE relinquishing mobility control to the RAN as aresult of the reactivation of the suspended RRC connection or a normalRRC connection process to establish a new RRC connection with the UE.

16. A method as set out in clause 15, wherein when the UE selects a cellof the RAN in which the suspended RRC Connection represented by thestored RRC connection data is invalid, the UE continues to store the RRCconnection data and omits to perform any communication with the CN toinform the CN of the mobility of the UE.17. A method as set out in clause 15, wherein when the UE selects a cellof the RAN in which the suspended RRC Connection represented by thestored RRC connection data is invalid, the UE transmits a messageinforming the RAN or the CN of this event.18. A method as set out in clause 17, wherein the UE also releases theRRC connection and enters idle mode as the result of selecting a cell ofthe RAN in which the suspended RRC Connection represented by the storedRRC connection data is invalid.19. A method as set out in clause 17 or 18, wherein receipt by the RANor the CN of the message sent by the UE causes the RAN or CN to performone or more of: release the invalid RRC Connection; initiate a normalRRC connection process to establish a new RRC connection with the UE;release an established user plane connection for the UE between the CNand RAN.20. A method as set out in clause 15, wherein when the UE selects a cellof the RAN in which the suspended RRC Connection represented by thestored RRC connection data is invalid, the UE continues to store the RRCconnection data and transmits a message informing the RAN or the CN ofthis event.21. A method as set out in any preceding clause, further comprising:

-   -   the UE determining whether or not the suspended RRC connection        is still valid by reference to the stored RRC connection data;        and    -   in response to the UE determining that the suspended RRC        connection is still valid, the UE sending an RRC connection        reactivation request message to the RAN.        22. A method as set out in clause 21, further comprising:

in response to receiving an RRC connection reactivation complete messagefrom the RAN, the UE resuming user plane data transfer with the RAN overthe reactivated RRC connection.

23. A method as set out in clause 22, further comprising:

in response to receiving an RRC connection reactivation reject messagefrom the RAN, the UE releasing the suspended RRC connection and enteringidle mode; and

the UE thereafter initiating a normal RRC connection establishmentprocess to establish a new RRC connection with the RAN.

24. A method of clause 23, wherein a RAN node transmits the RRCconnection reactivation reject message to the UE in response to the RANnode determining that it does not have a valid suspended RRC connectionfor the UE.25. A method as set out in any preceding clause, further comprising;

the UE determining whether or not the suspended RRC connection is stillvalid by reference to the stored RRC connection data;

in response to the UE determining that the suspended RRC connection isinvalid, the UE releasing the suspended RRC connection and entering idlemode; and

the UE thereafter initiating a normal RRC connection establishmentprocess to establish a new RRC connection with the RAN.

26. A method of any of clauses 21 to 25, wherein the UE determiningwhether or not the suspended RRC connection is still valid composes atleast one of:

-   -   determining whether the UE is currently in a cell of the RAN in        which the suspended RRC Connection represented by the stored RRC        connection data is still valid; and    -   determining whether a timer has not expired.        27. A method of clauses 21-26, further comprising the UE        relinquishing mobility control of the UE to the RAN as a result        of the reactivation of the suspended RRC connection or the        establishment of a new RRC connection.        28. A method of any preceding clause, further comprising        initiating the reactivation of the suspended RRC connection in        response to:    -   the UE generating uplink data via the user plane of an RRC        connection; or    -   reception at the UE paging; or    -   reception at the UE of a notification that the RAN or the CN has        downlink data buffered to send to the UE.        29. A method as set out in any preceding clause, wherein the UE        is configured to communicate with the RAN in accordance with the        LTE or LTE Advanced protocols.        30. A method as set out in any preceding clause, wherein the RAN        is configured to communicate with the UE in accordance with the        LTE or LTE Advanced protocols.        31. A method as set out in any preceding clause, wherein the RAN        node or nodes is/are eNode B(s).

32. A User Equipment (UE) for use with a Radio Access Network (RAN), theUE being configured to:

suspend an established RRC connection with the RAN;

monitor, whilst the RRC connection is suspended, for at least one of:paging and notifications of downlink data for the UE; and

store RRC connection data representing the suspended RRC connection,said RRC connection data being usable by the UE to reactivate thesuspended RRC connection.

33. A UE as set out in clause 32, wherein RRC connection data comprisesdata representing one or more of:

-   -   the configuration of radio bearers in the established RRC        connection;    -   security parameters relating to the established RRC connection;    -   temporary cell identifiers;    -   MAC configuration;    -   Physical Layer configuration.        34. A UE as set out in clause 32 or 33, further comprising the        UE being configured to mark the stored RRC connection data to        indicate the suspension of the RRC connection.        35. A UE as set out in clause 32, 33 or 34, further comprising        the UE being configured to suspend the established RRC        connection in response to an RRC connection suspension criterion        being met.        36. A UE as set out in clause 35, wherein the RRC connection        suspension criteria comprise one or more of:    -   the expiry of a timer at the UE;    -   reception of a message at the UE.        37. A UE as set out in any of clauses 32-36, further comprising:

the UE being configured to perform autonomous mobility control by cellselection or reselection processes during the time that the RRCconnection is suspended and the UE relinquishing mobility control to theRAN as a result of an the reactivation of the suspended RRC connectionor a normal RRC connection process to establish a new RRC connectionwith the UE.

38. A UE as set out in clause 37, the UE being configured such that,when the UE selects a cell of the RAN in which the suspended RRCConnection represented by the stored RRC connection data is invalid, theUE continues to store the RRC connection data and omits to perform anycommunication with the CN to inform the CN of the mobility of the UE.39. A UE as set out in clause 37, the UE being configured such that,when the UE selects a cell of the RAN in which the suspended RRCConnection represented by the stored RRC connection data is invalid, theUE transmits a message informing the RAN or the CN of this event.40. A UE as set out in clause 39, the UE being configured such that theUE also releases the RRC connection and enters idle mode as the resultof selecting a cell of the RAN in which the suspended RRC Connectionrepresented by the stored RRC connection data is invalid.41. A UE as set out in clause 39 or 40, wherein receipt by the RAN orthe CN of the message sent by the UE causes the RAN or CN to perform oneor more of: releasing the invalid RRC Connection; initiating a normalRRC connection process to establish a new RRC connection with the UE;releasing an established user plane connection for the UE between the CNand RAN.42. A UE as set out in clause 37, the UE being configure such that, whenthe UE selects a cell of the RAN in which the suspended RRC Connectionrepresented by the stored RRC connection data is invalid, the UEcontinues to store the RRC connection data and transmits a messageinforming the RAN or the CN of this event.43. A UE as set out in any of clauses 32-42, further comprising the UEbeing configured such that, as part of the RRC connection reactivationprocess:

the UE determines whether or not the suspended RRC connection is stillvalid by reference to the stored RRC connection data; and

in response to the UE determining that the suspended RRC connection isstill valid, the UE sends an RRC connection reactivation request messageto the RAN.

44. A UE as set out in clause 43, further comprising:

the UE being configured such that, in response to receiving an RRCconnection reactivation complete message from the RAN, the UE resumesuser plane data transfer with the RAN over the reactivated RRCconnection.

45. A UE as set out in clause 43, further comprising:

the UE being configured such that, in response to receiving an RRCconnection reactivation reject message from the RAN, the UE releases thesuspended RRC connection and entering idle mode; and

the UE configured to thereafter initiate a normal RRC connectionestablishment process to establish a new RRC connection with the RAN.

46. A UE as set out in clause 43, wherein a RAN node transmits the RRCconnection reactivation reject message to the UE in response to the RANnode determining that it does not have a valid suspended RRC connectionfor the UE.47. A UE as set out in any of clauses 32-48, further comprising the UEbeing configured to:

determine whether or not the suspended RRC connection is still valid byreference to the stored RRC connection data;

in response to the UE determining that the suspended RRC connection isinvalid, release the suspended RRC connection and enters idle mode; and

thereafter initiate a normal RRC connection establishment process toestablish a new RRC connection with the RAN.

48. A UE as set out in any of clauses 43-47, further comprising the UEbeing configured to, as part of determining whether or not the suspendedRRC connection is still valid, determine at least one of:

-   -   whether the UE is currently in a cell of the RAN in which the        suspended RRC Connection represented by the stored RRC        connection data is still valid; and    -   whether a timer has not expired.        49. A UE as set out in any of clauses 43-48, further comprising        the UE being configured to relinquish mobility control of the UE        to the RAN as a result of the reactivation of the suspended RRC        connection or the establishment of a new RRC connection.        50. A UE as set out in any of clauses 32-49, further comprising        the UE being configured to initiate the reactivation of the        suspended RRC connection reactivation process in response to at        least one of:    -   the UE generating uplink data via the user plane of an RRC        connection;    -   reception at the UE of paging; and    -   reception at the UE of a message indicating that the RAN or the        CN has downlink data buffered to send to the UE over the user        plane of an RRC connection.        51. A UE as set out in any of clauses 32-50, wherein the UE is        configured to communicate with the RAN in accordance with the        LTE or LTE Advanced protocols.        52. A wireless communications system comprising a UE as set out        in any of clauses 32-51, and a RAN having an established user        plane connection with a Core Network (CN) for the UE, the system        being configured to maintain the established user plane        connection between the RAN and the CN while the RRC Connection        is suspended.        53. A wireless communications system as set out in clause 52,        further comprising the RAN node for which the suspended RRC        connection is valid being configured such that when the RAN node        receives from the CN downlink data for the UE, the RAN node        buffers the downlink data and pages the UE or transmits a        notification of downlink data for the UE.        54. A wireless communications system as set out in clause 53,        further comprising the RAN node being configured such that, in        response to the RAN node receiving no response from the UE to        the paging or to the notification of downlink data, the RAN node        sends to the CN a paging escalation message.        55. A wireless communications system comprising a UE as set out        in any of clauses 32-51, and a RAN, the wireless communications        system being configured such that the UE or a RAN node sends a        message to inform any node in the Core Network (CN) that the RRC        connection is suspended.        56. A wireless communications system as set out in clause 55,        wherein the RAN has an established user plane connection with        the CN for the UE, the wireless communications system being        configured such that the wireless communications system suspends        the established user plane connection between the CN and the        RAN.        57. A wireless communications system as set out in clause 56,        further comprising the wireless communications system being        configured such that the message sent to the CN includes an        identification of the UE, and such that, to suspend the        established user plane connection between the CN and the RAN,        the RAN or one or more nodes in the CN or both:

discontinue transmission and reception of user plane data for the UEover the user plane connection between the RAN and the CN; and

store CN-RAN connection data representing the established user planeconnection, said CN-RAN connection data being usable to later resumetransmission and reception of user plane data to the UE by resuming saiduser plane connection between the RAN and the CN as the result of an RRCconnection reactivation process.

58. A wireless communications system as set out in clauses 56 or 57,further comprising the wireless communications system being configuredsuch that, when downlink data for the UE is received at the CN, a nodeof the CN buffers the downlink data and the CN initiates the paging ofthe UE by one or more cells of the RAN.59. A wireless communications system as set out in clauses 55, 57 or 58,further comprising the wireless communications system being configuredsuch that a node of the CN maintains a validity indicator tor the UE,said validity indicator being usable in checking the validity of thesaid RRC connection as part of the RRC connection reactivation process.60. A wireless communications system as set out in clause 59, whereinthe value of the validity indicator is dependent on one or more of: thelocation of the UE; a timer.61. A wireless communications system as set out in any of clauses 52-60,wherein the RAN is configured to communicate with the UE in accordancewith the LTE or LTE Advanced protocols.62. A wireless communications system as set out in any of clauses 52-60,wherein the RAN node or nodes is/are eNode B(s).63. A computer program product having instructions which when carriedout by a processor of User Equipment (UE) for use with a Radio AccessNetwork (RAN) cause the UE to be configured to operate in accordancewith a method as set out in any of clauses 1-31.64. A computer program product having instructions which when carriedout by a processor of a node of a Radio Access Network (RAN) for usewith a user equipment (UE) cause the RAN node to be configured tooperate in accordance with a method as set out in any of clauses 1-31.

Aspects of the present disclosure relating to the operation of a RANnode to suspend ah RRC connection will now be set out in the followingnumbered clauses.

1. A method, implemented in a node of a Radio Access Network (RAN) foruse with a user equipment (UE), comprising:

the RAN node suspending an established RRC connection with the UE;

the RAN node thereafter being operable, whilst the RRC connection issuspended, to page the UE paging or transmit notification of downlinkdata for the UE or both; and

the RAN node storing RRC connection data related to the suspended RRCconnection, said RRC connection data being usable by the RAN node toreactivate the suspended RRC connection.

2. A method as set out in clause 1, wherein RRC connection datacomprises data representing one or more of:

-   -   the configuration of radio bearers in the established RRC        connection;    -   security parameters relating to the established RRC connection;    -   temporary cell identifiers;    -   MAC configuration;    -   Physical Layer configuration.

3. A method as set out in clause 1 or 2, further comprising marking thestored RRC connection data to indicate the suspension of the RRCconnection.

4. A method as set out in clause 1, 2 or 3 wherein the RAN node suspendsthe established RRC connection in response to an RRC connectionsuspension criterion being met.

5. A method as set out in clause 4, the RRC connection suspensioncriteria comprising one or more of:

-   -   the expiry of a timer at the RAN Node;    -   transmission Of a message by the RAN node to the UE to instruct        suspension of the established RRC Connection.

6. A method as set out in any of clauses 1-5, wherein the RAN node hasan established user plane connection with a Core Network (CN) for theUE, the method further comprising maintaining the established user planeconnection between the RAN node and the CN while the RRC Connection issuspended.

7. A method as set out in clause 6, wherein when the RAN node receivesfrom the CN downlink data for the UE, the RAN node buffers the downlinkdata and pages the UE a or transmits a notification of downlink data forthe UE.

8. A method as set out in clause 7, wherein, in response to the RAN nodereceiving no response from the UE to the paging or to the notificationof downlink data, the RAN node sends to the CN a paging escalationmessage.

9. A method as set out in any of clauses 1-5, further comprising the UEor the RAN node sending a message to inform any node in the Core Network(CN) that the RRC connection is suspended.

10. A method as set out in clause 9, wherein the RAN node has anestablished user plane connection with a CN for the UE, the methodfurther comprising suspending the established user plane connectionbetween the CN and the RAN for the UE.

11. A method as set out in clause 10, wherein the message sent to the CNincludes an identification of the UE, the method further comprising theRAN node or one or more ON nodes or both:

discontinuing transmission and reception of user plane data for the UEover the established user plane connection between the CN and the RANnode; and

storing CN-RAN connection data representing the established user planeconnection with the CN, said CN-RAN Connection data being usable tolater resume transmission and reception of user plane data to the UE byreactivating said user plane connection between the CN and the RAN nodeas the result of an RRC connection reactivation process.

12. A method as set out in clauses 10 or 11, wherein when downlink datafor the UE is received at the CN, a node of the CN buffers the downlinkdata and the CN initiates the paging of the UE by one or more cells ofthe RAN.

13. A method as set out in clauses 10, 11 or 12, further comprising anode of the CN maintaining a validity indicator for the UE, saidvalidity indicator being usable in checking the validity of the said RRCconnection as part of the RRC connection reactivation process.

14. A method as set out in clause 13, wherein the value of the validityindicator is dependent on one or more of: the location of the user; atimer.

15. A method as set out in any preceding clause, further comprising:

the RAN relinquishing to the UE, mobility control of the UE until theRAN resumes mobility control of the UE as the result of the reactivationof the suspended RRC connection or a normal RRC connection process toestablish a new RRC connection with the UE.

16. A method as set out in clause 15, wherein when the UE selects a cellof the RAN in which the suspended RRC Connection represented by thestored RRC connection data is invalid, the RAN receiving a messageinforming the RAN of this event.

17. A method as set out in clause 16, wherein receipt by the RAN of themessage sent by the UE causes the RAN to perform one or more of: releasethe invalid suspended RRC Connection; initiate a new RRC connection withthe UE; release an established user plane connection for the UE betweenthe CN and RAN.

18. A method as set out in clause 15, 16 or 17, further composing theRAN resuming mobility control of the UE as a result of reactivation ofthe suspended RRC connection or a normal RRC connection process toestablish a new RRC connection with the UE.

19. A method as set out in any preceding clause, wherein the RAN node/inresponse to receiving an RRC connection reactivation request messagefrom the UE:

determining whether or not the suspended RRC connection is still validby reference to the stored RRC connection data; and

in response to the RAN node determining that the suspended RRCconnection is still valid, sending a reactivation request completemessage to the UE and thereafter resuming user plane data transfer withthe UE over the reactivated RRC connection; or

in response to the RAN node determining that the suspended RRCconnection is invalid, sending a reactivation request reject message tothe UE.

20. A method as set out in clause 19, wherein the RAN node determiningwhether or not the suspended RRC connection is still valid comprises atleast one of:

-   -   determining that a timer has not expired; and    -   determining that the RRC connection has not been released.

21. A method as set out in any preceding clause, wherein the UE isconfigured to communicate with the RAN in accordance with the LTE or LTEAdvanced protocols.

22. A method as set out in any preceding clause, wherein the RAN isconfigured to communicate with the UE in accordance with the LTE or LTEAdvanced protocols.

23. A method as set out in any preceding clause, wherein the RAN node ornodes is/are eNode B(s).

24. A node of a Radio Access Network (RAN) for use with a user equipment(UE), the RAN node being configured to:

suspend an established RRC connection with the UE;

thereafter be operable, whilst the RRC connection is suspended, to pagethe UE or transmit notification of downlink data for the UE or both; and

store RRC connection data related to the suspended RRC connection, saidRRC connection data being usable by the RAN node reactivate thesuspended RRC connection.

25. A RAN node as set out in clause 24, wherein RRC connection datacomprises data representing one or more of:

-   -   the configuration of radio bearers in the established RRC        connection;    -   security parameters relating to the established RRC connection;    -   temporary cell identifiers;    -   MAC configuration;    -   Physical Layer configuration.

26. A RAN node as set out in clause 24 or 25, further comprising markingthe stored RRC connection data to indicate the suspension of the RRCconnection.

27. A RAN node as set out in clause 24, 25 or 26, further comprising theRAN node being configured to suspend the established RRC connection inresponse to an RRC connection suspension criterion being met

28. A RAN node as set out in clause 27, wherein the RRC connectionsuspension criteria comprises one or more of:

-   -   the expiry of a timer at the RAN Node;    -   transmission of a message by the RAN node to the UE to instruct        suspension of the established RRC connection.

23. A RAN node as set out in any of clauses 24-28, further comprisingthe RAN node being configure to, in response to receiving an RRCconnection reactivation request message from the UE:

determine whether or not the suspended RRC connection is still valid byreference to the stored RRC connection data;

in response to the RAN node determining that the suspended RRCconnection is still valid, send a reactivation request complete messageto the UE and thereafter resuming user plane data transfer with the UEover the reactivated RRC connection; and

in response to the RAN node determining that the suspended RRCconnection is invalid, send a reactivation request reject message to theUE.

30. A RAN node as set out in clause 29, the RAN node being configuredsuch that the RAN node determining whether or not the suspended RRCconnection is still valid comprises at least one of:

-   -   determining that a timer has not expired; and    -   determining that the RRC connection has not been released.

31. A RAN node as set out in clause 29 or 30, further comprising the RANresuming mobility control of the UE as a result of reactivation of thesuspended RRC connection or a normal RRC connection process to establisha new RRC connection with the UE.

32. A RAN node as set out in any of clauses 24-31, wherein the RAN nodeis configured to communicate with the UE in accordance with the LTE orLTE Advanced protocols.

33. A RAN node as set out in any preceding clause, wherein the RAN nodeis an eNode B.

34. A RAN node as set out in any of clauses 24-33, wherein the RAN nodehas an established user plane connection with a Core Network (CN) forthe UE, further comprising maintaining the established user planeconnection between the RAN node and the CN while the RRC Connection issuspended.

35. A RAN node as set out in clause 34, the RAN node being configuredsuch that, when the RAN node receives from the CN downlink data for theUE, the RAN node buffers the downlink data and pages the UE or transmitsa notification of downlink data for the UE.

36. A RAN node as set out in clause 35, the RAN node being configuredsuch that, in response to the RAN node receiving no response from the UEto the paging or to the notification of downlink data, the RAN nodesends to the CN a paging escalation message.

37. A RAN node as set out in any of clauses 24-33, further comprisingthe UE or the RAN node sending a message to inform any node in the CoreNetwork (CN) that the RRC connection is suspended.

38. A RAN node as set out in clause 37, wherein the RAN node has anestablished user plane connection with a CN for the UE, furthercomprising suspending the established user plane connection between theCN and the RAN for the UE.

39. A RAN node as set out in clause 38, wherein the message sent to theCN includes an identification of the UE, the RAN node or one or more CNnodes or both being configured to:

discontinue transmission and reception of user plane data for the UEover the established user plane connection between the CN and the RANnode; and

store CN-RAN connection data representing the established user planeconnection with the CN, said CN-RAN connection data being usable tolater resume transmission and reception of user plane data to the UE byresuming said user plane connection between the CN and the RAN node asthe result of an RRC connection reactivation process.

40. A wireless communication system comprising a RAN node as set out inclauses 38 or 39 and a CN, wherein the CN is configured such that whendownlink data for the UE is received at the CN, a node of the CN buffersthe downlink data and the CN initiates the paging of the UE by one ormore cells of the RAN.

41. A wireless communication system comprising a RAN node as set out inclauses 38 or 39 and a CN or a wireless communication system as set outin clause 40, further comprising the wireless communication system beingconfigured such that a node of the CN maintains a validity indicator forthe UE, said validity indicator being usable in checking the validity ofthe said RRC connection as part of the RRC connection reactivationprocess.

42. A wireless communication system as set out in clause 41, wherein thevalue of the validity indicator is dependent on one or more of: thelocation of the user; a timer.

43. A RAN including a RAN node as set out in any of clauses 24-39,further comprising:

the RAN being configured to relinquish to the UE, mobility control ofthe UE until the RAN resumes mobility control of the UE as the result ofan RRC connection reactivation process or a normal RRC connectionprocess to establish a new RRC connection with the UE.

44. A RAN as set out in clause 43, wherein when the UE selects a cell ofthe RAN in which the suspended RRC Connection represented by the storedRRC connection data is invalid, the RAN receives a message informing theRAN of this event.

45. A RAN as set out in clause 44, wherein the RAN is configured suchthat receipt by the RAN of the message sent by the UE causes the RAN toperform one or more of: release the invalid suspended RRC Connection;initiate a new RRC connection with the UE; release an established userplane connection for the UE between the CN and RAN.

46. A computer program product having instructions which when carriedout by a processor of a node of a Radio Access Network (RAN) for usewith a user equipment (UE) cause the RAN node to be configured tooperate in accordance with a method as set out in any of clauses 1-23.

Aspects of the present disclosure relating to the operation of a CN nodeto suspend an RRC connection will now be set out in the followingnumbered clauses.

1. A method, implemented in a node of a Core Network (CN) for use with anode of a Radio Access Network (RAN), comprising, in response to the CNreceiving a message indicating that an RRC connection between the RANand a user equipment (UE) is suspended:

the CN node discontinuing transmission and reception of user plane datafor the UE over an established user plane CN-RAN connection between theCN and the RAN node; and

storing CM-RAN connection data representing the established user planeconnection with the CN, said CN-RAN connection data being usable tolater resume transmission and reception of user plane data to the UE byresuming said user plane connection between the CN and the RAN node asthe result of the RRC connection being reactivated.

2. A method as set out in clause 1, wherein when downlink data for theUE is received at the CN, the method further comprising buffering thedownlink data in a node of the CN and initiating the paging of the UE byone or more cells of the RAN.

3. A method as set out in clause 1 or 2, further comprising, in responseto receiving a CN-RAN connection reactivation, message at a node of theCN, resuming user plane data transfer between the CN and the RAN.

4. A method as set out in any preceding clause, wherein the CN node ispart of an Evolved Packet Core (EPC) configured to communicate inaccordance with the LTE or LTE Advanced protocols.

5. A node of a Core Network (CN) for use with a Radio Access Network(RAN), the node of the CN being configured to, in response to the CNreceiving a message indicating that an RRC connection between the RANand a user equipment (UE) is suspended:

discontinue transmission and reception of user plane data for the UEover an established user plane CN-RAN connection between the CN and theRAN node; and

store CN-RAN connection data representing the established user planeconnection with the CN, said CN-RAN connection data being usable tolater resume transmission and reception of user plane data to the UE byresuming said user plane connection between the CN and the RAN node asthe result of the RRC connection being reactivated.

6. A CN node as set out in clause 5, the CN node being configured suchthat, when downlink data for the UE is received at the CN, the CN nodebuffers the downlink data and initiates the paging of the UE by one ormore cells of the RAN.

7. A CN node as set out in clause 5 or 6, further comprising the CNnode, in response to receiving a CN-RAN connection reactivation messageat a node of the CN, resuming user plane data transfer with the RAN.

8. A CN node as set out in clause 5, 6 or 7, wherein the CN node is partof an Evolved Packet Core (EPC) configured to communicate in accordancewith the LTE or LTE Advanced protocols.

9. A computer program product having instructions which when carried outby a processor of a node of a Core Network (CN) for use with a RadioAccess Network (RAN) cause the node of the CN to be configured tooperate in accordance with a method as set cot in any of clauses 1-4.

Aspects of the present disclosure relating to the operation of a UE or aRAN node for assessing the validity of a suspended RRC connection andreactivating a suspended RRC connection will now be set out in thefollowing numbered clauses.

1. A method, implemented in a node of a Radio Access Network (RAN) foruse with a user equipment (UE), an established RRC connection betweenthe RAN node and a UE having been suspended and RRC connection datarelated to the suspended RRC connection having been stored by the RANnode, the method comprising:

receiving at the RAN node an RRC connection reactivation request messagefrom the UE;

determining whether or not the suspended RRC connection is stiff validby reference to the stored RRC connection data; and

in response to the RAN node determining that the suspended RRCconnection is still valid, the RAN node sending a reactivation requestcomplete message to the UE and thereafter resuming user plane datatransfer with the UE over the reactivated RRC connection; or

in response to the RAN node determining that the suspended RRCconnection is invalid, the RAN node sending a reactivation requestreject message to the RAN.

2. A method as set out in clause 1, wherein the RAN node determiningwhether or not the suspended RRC connection is still valid comprises atleast one of:

-   -   determining that a timer has not expired; and    -   determining that the RRC connection has not been released.

3. A method as set out in clause 1 or 2, further comprising the RANresuming mobility control of the UE from the UE as a result ofreactivation of the suspended RRC connection or a normal RRC connectionprocess to establish a new RRC connection with the UE.

4. A method as set out in any preceding clause, wherein the RAN node ornodes is/are configured to communicate with the UE in accordance withthe LTE or LTE Advanced protocols.

5. A method as set out in any preceding clause, wherein the RAN node ornodes is/are eNode B(s).

6. A node of a Radio Access Network (RAN) for use with a user equipment(UE), the RAN node being configured such that when an established RRCconnection between the RAN node and a UE has been suspended and RRCconnection data related to the suspended RRC connection has been storedby the RAN node, in response to receiving at the RAN node an RRCconnection reactivation request message from the UE:

the RAN node determines whether or not the suspended RRC connection isstill valid by reference to the stored RRC connection data;

in response to the RAN node determining that the suspended RRCconnection is still valid, the RAN node sends a reactivation requestcomplete message to the UE and thereafter resuming user plane datatransfer with the UE over the reactivated RRC connection; and

in response to the RAN node determining that the suspended RRCconnection is invalid, the RAN node sends a reactivation request rejectmessage to the RAN.

7. A RAN node as set out in clause 6, further comprising the RAN nodebeing configured to determine whether or not the suspended RRCconnection is still valid by at least one of the RAN node:

-   -   determining that a timer has not expired; and    -   determining that the RRC connection has not been released.

8. A RAN comprising a RAN node as set out in clause 5 or 6, the RANbeing configured to resume mobility control of the UE from the UE as aresult of reactivation of the suspended RRC connection or a normal RRCconnection process to establish a new RRC connection with the UE.

9. A RAN node as set out in any of clauses 5-8, the RAN node or nodesbeing configured to communicate with the UE in accordance with the LTEor LTE Advanced protocols.

10. A RAN node as set out in any of clauses 5-9, wherein the RAN node ornodes is/are eNode B(s).

11. A computer program product having instructions which when carriedout by a processor of a node of a Radio Access Network (RAN) for usewith a user equipment (UE) cause the RAN node to be configured tooperate in accordance with a method as set out in any of clauses 1-5.

12. A method, implemented in a user equipment (UE) for use with a RadioAccess Network (RAN), an established RRC connection between a node ofthe RAN and the UE having been suspended and RRC connection data relatedto the suspended RRC connection having been stored by the UE, the methodcomprising:

the UE determining whether or not the suspended RRC connection is stillvalid by reference to the stored RRC connection data; and

in response to the UE determining that the suspended RRC connection isstill valid, the UE: transmitting to the RAN node an RRC connectionreactivation request message; and, in response to receiving from the RANnode an RRC connection reactivation accept message, the UE thereafterresuming user plane data transfer with the RAN node over the reactivatedRRC connection, or in response to receiving from the RAN node an RRCconnection reactivation reject message, the UE releasing the RRCconnection; or

in response to the UE determining that the suspended RRC connection isinvalid, the UE releasing the RRC connection.

13. A method as set out in clause 12, wherein the UE determining whetheror not the suspended RRC connection is still valid comprises at leastone of:

-   -   determining whether the UE is currently in a cell of the RAN in        which the suspended RRC Connection represented by the stored RRC        connection data is still valid; and    -   determining whether a timer has not expired.

14. A method as set out in clause 12 or 13, further comprising, inresponse to receiving RRC connection reactivation reject message or theUE determining that the suspended RRC connection is invalid, the UE alsoentering idle mode and thereafter initiating a normal RRC connectionestablishment process to establish a new RRC connection with the RAN.

15. A method as set out in clause 12, 13 or 14, further comprising theUE relinquishing mobility control of the UE to the RAN as a result ofreactivation of the suspended RRC connection or a normal RRC connectionprocess to establish a new RRC connection with the RAN.

16. A method as set out in any of clauses 12-15, wherein the UE isconfigured to communicate with the RAN in accordance with the LTE or LTEAdvanced protocols.

17. A User Equipment (UE) for use with a Radio Access Network (RAN), theUE being configured such that when an established RRC connection betweena node of the RAN and the UE has been suspended and RRC connection datarepresenting configuration information and state information related tothe suspended RRC connection has been stored by the UE:

the UE determines whether or not the suspended RRC connection is stillvalid by reference to the stored RRC connection data;

in response to the UE determining that the suspended RRC connection isstill valid, the UE transmits to the RAN node an RRC connectionreactivation request message; and, in response to receiving from the RANnode an RRC connection reactivation accept message, the UE thereafterresumes user plane data transfer with the RAN node over the reactivatedRRC connection, or in response to receiving from the RAN node an RRCconnection reactivation reject message, the UE releases the RRCconnection; and

in response to the UE determining that the suspended RRC connection isinvalid, the UE releases the RRC connection.

18. A UE set out in clause 17, further comprising the UE beingconfigured to determine whether or not the suspended RRC connection isstill valid by at least one of the UE;

-   -   determining whether the UE is currently in a cell of the RAN in        which the suspended RRC Connection represented by the stored RRC        connection data is still valid; and    -   determining whether a timer has not expired.

19. A UE as set out in clause 17 or 18, further comprising the UE beingconfigured such that, in response to receiving RRC connectionreactivation reject message or the UE determining that the suspended RRCconnection is invalid, the UE also enters idle mode and thereafterinitiates a normal RRC connection establishment process to establish anew RRC connection with the RAN.

20. A UE as set out in clause 17, 18 or 19, further comprising the UEbeing configured to relinquish mobility control of the UE to the RAN asa result of the reactivation of the suspended RRC connection or a normalRRC connection process to establish a new RRC connection with the RAN.

21. A UE as set out in any of clauses 17-20, wherein the UE isconfigured to communicate with the RAN in accordance with the LTE or LTEAdvanced protocols.

22. A computer program product having instructions which when carriedout by a processor of User Equipment (UE) for use with a Radio AccessNetwork (RAN) connection cause the UE to be configured to operate inaccordance with a method as set out in any of clauses 12-16.

Aspects of the present disclosure relating to the operation of a CN nodeor a RAN node for handling downlink data while an RRC connection issuspended will now be set out in the following numbered clauses.

1. A method, implemented in a node of a Radio Access Network (RAN) foruse with a user equipment (UE), an established RRC connection between aRAN node and a UE having been suspended and RRC connection data relatedto the suspended RRC connection having been stored by the RAN node, themethod comprising:

the RAN node receiving downlink data for the UE;

the RAN node buffering the downlink data; and

the RAN node paging the UE or transmitting notification of downlink,data for the UE.

2. A method as set out in clause 1, wherein, in response to the RAN nodereceiving no response from the UE to the paging or to the notificationof downlink data, the RAN node sends to the CN a paging escalationmessage.

3. A method as set out in clause 2, further comprising:

receiving at the RAN node an RRC connection reactivation request messagefrom the UE;

determining whether or not the suspended RRC connection is still validby reference to the stored RRC connection data; and

in response to the RAN node determining that the suspended RRCconnection is still valid, the RAN node sending a reactivation requestcomplete message to the UE and thereafter resuming user plane datatransfer with the UE over the reactivated RRC connection; or

in response to the RAN node determining that the suspended RRCconnection is invalid, the RAN node sending a reactivation requestreject message to the RAN.

4. A method as set out in any preceding clause, wherein the RAN node isconfigured to communicate with the UE in accordance with the LTE or LTEAdvanced protocols.

5. A method as set out in any preceding clause, wherein the RAN node isan eNode B.

6. A node of a Radio Access Network (RAN) for use with a user equipment(UE), the RAN node being configured such that when an established RRCconnection between the RAN node and a UE has been suspended and RRCconnection date related to the suspended RRC connection has been storedby the RAN node, in response to the RAN node receiving downlink data forthe UE:

the RAN node buffers the downlink data; and

the RAN node pages the UE or transmits a message giving notification ofdownlink data.

7. A RAN node as set out in clause 6, the RAN node being configured suchthat, in response to the RAN node receiving no response from the UE tothe paging message or to the message giving notification of downlinkdata, the RAN node sends to the CN a paging escalation message.

8. A RAN node as set out in clause 6, further comprising the RAN nodebeing configured such that, in response to the RAN node receiving an RRCconnection reactivation request message from the UE:

the RAN node determines whether or not the suspended RRC connection isstill valid by reference to the stored RRC connection date;

in response to the RAN node determining that the suspended RRCconnection is still valid, the RAN node sends a reactivation requestcomplete message to the UE and thereafter resuming user plane datatransfer with the UE over the reactivated RRC connection; and

in response to the RAN node determining that the suspended RRCconnection is invalid, the RAN node sends a reactivation request rejectmessage to the RAN.

9. A RAN node as set out in any of clauses 6-8, wherein the RAN node isconfigured to communicate with the UE in accordance with the LTE or LTEAdvanced protocols.

10. A method as set out in any of clauses 8-9, wherein the RAN node isan eNode B.

11. A computer program product having instructions which when carriedout by a processor of a node of a Radio Access Network (RAN) for usewith a user equipment (UE) cause the RAN node to be configured tooperate in accordance with a method as set out in any of clauses 1-5.

12. A method, implemented in a node of a Core Network (CN) for use witha node of a Radio Access Network (RAN), the transmission and receptionof user plane data for a user equipment (UE) over an established userplane CN-RAN connection for the UE between the CN and the RAN nodehaving been discontinued in response to the CN receiving a messageindicating that an RRC connection between the RAN and the UE issuspended and CN-RAN connection data representing the extant user planeconnection between the CN and the RAN having been stored, the methodcomprising:

receiving downlink data for the UE;

the CN node buffering the downlink data;

the CN node initiating the paging of the UE by one or more cells of theRAN.

13. A method as set out in clause 12, further comprising a node of theCN maintaining a validity indicator for the UE, said validity indicatorbeing usable in checking the validity of the said RRC connection as partof a RRC connection reactivation process.

14. A method as set out in clause 13, wherein the value of the validityindicator is dependent on one or more of: the location of the user; atimer.

15. A method as set out in any of clauses 12-14, wherein the CN node ispart of an Evolved Packet Core (EPC) configured to communicate inaccordance with the LTE or LTE Advanced protocols.

16. A node of a Core Network (CN) for use with a node of a Radio AccessNetwork (RAN), the CN node being configured such that when thetransmission and reception of user plane data for a user equipment (UE)over an established user plane CN-RAN connection for the UE between theCN end the RAN node has been discontinued in response to the CNreceiving a message indicating that an RRC connection between the RANand the UE is suspended and CN-RAN connection data representing theextant user plane connection between the CN and the RAN has been stored,in response to receiving downlink data for the UE:

the CN node buffers the downlink data;

the CN node initiates the paging of the UE by one or more cells of theRAN.

17. A CN node as set out in clause 16, further comprising a node of theCN maintaining a validity indicator for the UE, said validity indicatorbeing usable in checking the validity of the said RRC connection as partof a RRC connection reactivation process.

18. A CN node as set out in clause 17, wherein the value of the validityindicator is dependent on one or more of: the location of the user; atimer.

19. A CN node as set out in any of clauses 16-18, wherein the CN node ispart of an Evolved Packet Core (EPC) configured to communicate inaccordance with the LTE or LTE Advanced protocols.

20. A computer program product having instructions which when carriedout by a processor of a node of a Core Network (CN) for communicatingwith a Radio Access Network (RAN) via a CN-RAN connection cause the nodeof the CN to be configured to operate in accordance with a method as setout in any of clauses 12-15.

Aspects of the present disclosure relating to the operation of a UE forhandling mobility of the UE while an RRC connection is suspended willnow be set out in the following numbered clauses.

1. A method, implemented in a user equipment (UE) for use with a RadioAccess Network (RAN), an established RRC connection between a node ofthe RAN and the UE having been suspended and RRC connection data relatedto the suspended RRC connection having been stored by the UE, the methodcomprising:

the UE performing autonomous mobility control by cell selection orreselection processes during the time that the RRC connection issuspended and the UE relinquishing mobility control of the UE to the RANas a result of reactivation of the suspended RRC connection or a normalRRC connection process to establish a new RRC connection with the UE.

2. A method as set out in clause 1, wherein when the UE selects a cellof the RAN in which the suspended RRC connection represented by the RRCconnection data is invalid, the UE continues to store the RRC connectiondata and omits to perform any communication with the CN to inform the CNof the mobility of the UE.

3. A method as set out in clause 1, wherein when the UE selects a cellof the RAN in which the suspended RRC connection represented by thestored RRC connection data is invalid, the UE transmits a messageinforming the RAN or a core network (CN) of this event.

4. A method as set out in clause 3, wherein the UE also releases thesuspended RRC connection end enters idle mode as the result of selectinga cell of the RAN in which the RRC connection represented by the storedRRC connection data is invalid.

5. A method as set out in any preceding clause, wherein the UE isconfigured to communicate with the RAN in accordance with the LTE or LTEAdvanced protocols.

6. A User Equipment (UE) for communicating with a Radio Access Network(RAN), the UE being configured such that when an established RRCconnection between a node of the RAN and the UE has been suspended andRRC connection data related to the suspended RRC connection has beenstored by the UE:

the UE performs autonomous mobility control by cell selection orreselection processes, during the time that the RRC connection issuspended; and

the UE relinquishes mobility control of the UE to the RAN as a result ofthe reactivation of the suspended RRC connection or a normal RRCconnection process to establish a new RRC connection with the UE.

7. A UE as set out in clause 6, further comprising the UE beingconfigured such that, when the UE selects a cell of the RAN in which thesuspended RRC connection represented by the RRC connection data isinvalid, the UE continues to store the RRC connection data and omits toperform any communication with the CN to inform the CN of the mobilityof the UE.

8. A UE as set out in clause 6, further comprising the UE beingconfigured such that, when the UE selects a cell of the RAN in which thesuspended RRC connection represented by the stored RRC connection datais invalid, the UE transmits a message informing the RAN or a corenetwork (ON) of this event.

9. A UE as set out in clause 8, further comprising the UE beingconfigured such that the UE also releases the suspended RRC connectionand enters idle mode as the result of selecting a cell of the RAN inwhich the RRC connection represented by the stored RRC connection datais invalid.

10. A UE as set out in any of clauses 8-9, wherein the UE is configuredto communicate with the RAN in accordance with the LTE or LTE Advancedprotocols.

11. A computer program product having instructions which when carriedout by a processor of User Equipment (UE) for use with a Radio AccessNetwork (RAN) connection cause the UE to be configured to operate inaccordance with a method as set out in any of clauses 1-5.

1-64. (canceled)
 65. A method, comprising: suspending, by a first CoreNetwork (CN) node, an established user plane connection between a RadioAccess Network (RAN) node and a second CN node, wherein the suspendingcauses the second CN node to release the established user planeconnection to become a suspended user plane connection; in response tothe suspending, storing, at the first CN node, CN-RAN connection datarepresenting the established user plane connection; receiving, at thefirst CN node, a connection reactivation message indicating a resumptionof the suspended user plane connection; and resuming the suspended userplane connection, wherein the resuming is based on the stored CN-RANconnection data being valid.
 66. The method of claim 65, wherein whetherthe stored CN-RAN connection data is valid is determined based on avalidity indicator stored at the first CN node.
 67. The method of claim66, wherein the validity indicator is determined based on at least oneof: a location of the UE, or a timer.
 68. The method of claim 65,wherein the CN-RAN connection data includes user plane bearer contextassociated with the UE.
 69. The method of claim 65, wherein the first CNnode and the second CN node are part of an Evolved Packet Core (EPC)that communicates in accordance with Long-Term Evolution (LTE) or LTEAdvanced protocols.
 70. The method of claim 65, wherein the first CNnode is a mobility management entity (MME), and the second CN node is aserving gateway (S-GW).
 71. The method of claim 65, wherein theestablished user plane connection and the suspended user planeconnection are associated with a user equipment.
 72. A first CoreNetwork (CN) node, comprising: a memory; and at least one hardwareprocessor communicatively coupled with the memory and configured to:suspend an established user plane connection between a Radio AccessNetwork (RAN) node and a second CN node, wherein the suspending causesthe second CN node to release the established user plane connection tobecome a suspended user plane connection; in response to the suspending,store CN-RAN connection data representing the established user planeconnection; receive a connection reactivation message indicating aresumption of the suspended user plane connection; and resume thesuspended user plane connection, wherein the resuming is based on thestored CN-RAN connection data being valid.
 73. The first CN node ofclaim 72, wherein whether the stored CN-RAN connection data is valid isdetermined based on a validity indicator stored at the first CN node.74. The first CN node of claim 73, wherein the validity indicator isdetermined based on at least one of: a location of the UE, or a timer.75. The first CN node of claim 72, wherein the CN-RAN connection dataincludes user plane bearer context associated with the UE.
 76. The firstCN node of claim 72, wherein the first CN node and the second CN nodeare part of an Evolved Packet Core (EPC) that communicates in accordancewith Long-Term Evolution (LTE) or LTE Advanced protocols.
 77. The firstCN node of claim 72, wherein the first CN node is a mobility managemententity (MME), and the second CN node is a serving gateway (S-GW). 78.The first CN node of claim 72, wherein the established user planeconnection and the suspended user plane connection are associated with auser equipment.
 79. A non-transitory computer-readable medium containinginstructions which, when executed, cause a first Core Network (CN) nodeto perform operations comprising: suspending an established user planeconnection between a Radio Access Network (RAN) node and a second CNnode, wherein the suspending causes the second CN node to release theestablished user plane connection to become a suspended user planeconnection; in response to the suspending, storing CN-RAN connectiondata representing the established user plane connection; receiving aconnection reactivation message indicating a resumption of the suspendeduser plane connection; and resuming the suspended user plane connection,wherein the resuming is based on the stored CN-RAN connection data beingvalid.
 80. The non-transitory computer-readable medium of claim 79,wherein whether the stored CN-RAN connection data is valid is determinedbased on a validity indicator stored at the first CN node.
 81. Thenon-transitory computer-readable medium of claim 80, wherein thevalidity indicator is determined based on at least one of: a location ofthe UE, or a timer.
 82. The non-transitory computer-readable medium ofclaim 79, wherein the CN-RAN connection data includes user plane bearercontext associated with the UE.
 83. The non-transitory computer-readablemedium of claim 79, wherein the first CN node and the second CN node arepart of an Evolved Packet Core (EPC) that communicates in accordancewith Long-Term Evolution (LTE) or LTE Advanced protocols.
 84. Thenon-transitory computer-readable medium of claim 79, wherein the firstCN node is a mobility management entity (MME), and the second CN node isa serving gateway (S-GW).